What I've been using instead of Hydroguard and why, plus some ranting

This thread is meant to be informative but not suggestive. DO NOT BLINDLY FOLLOW THIS ADVICE, BUT PLEASE DO COMMENT!

Hydroguard is expensive, and as I’ve found has a shelf life (6 months from opening bottle) as well as an expiry (can’t sit on shelf for 2 years) – so getting a good bottle is key, and not always possible depending on location and what stores import it or sell it. It also has strict requirements on storage, let it get too warm and I believe it is not as effective as it should be any longer.

From my research, there appear to be two main camps of hydroponic growers:

  1. Those that maintain a “sterile” reservoir, or one without beneficial bacteria or any bacteria at all for that matter.
  2. Those that maintain a “living” reservoir, or one that contains beneficial bacteria which should (in theory) keep the bad stuff in check given the proper conditions and treatment.

Most of the recommendations on this forum, if not all of them, lean toward #2. Both of these styles have their pros/cons, and their own sets of parameters and norms. I have found that the existing environment (or ability to change that environment as needed) is the single-biggest factor as to whether or not the grow will be successful when applied, i.e. in either case it boils down to “what works for you” and “how much you’re willing to change it to get it to work”.

In my case, I can’t change the air quality in my condo without doing extensive renovations or purchasing expensive air purifying devices, and I rent, so finding something that works without “dealing with the dust first” was paramount to me. Additionally, it gets hot and humid here in the summer, and my A/C unit is literally glued into the wall (contributing to the dust coming in, can’t replace it with better unit + hepa filter), I can’t change the filter, so that leads to me doing things like vacuuming it out and spraying it with compressed air cans to get it to blow cold again and that only deals with part of the issue it poses.

I’m a noob in growing hydro (started 6 months ago) but do consider myself to be a man of science and can get quite technical. I do have experience growing in soil, mostly from being around outdoor growers for most of my life but also from having done so myself.

From my own experimentation in the grobo, this is what worked for me (and wasn’t hard to try):

  1. Unplug bottles #1 and #2, as the second bottle states it’s not to be mixed with what is about to be added. Bottle #1 won’t be much use without #2 anyway. This also can help to avoid undesirable “pH swings” early on in the plants’ life.

  2. Make sure to be filling with distilled water (not “spring water”, it must say “distilled water” on the bottle). It’s already close enough in pH to what these plants like, I’ve found it possible to grow without pH up and down when using this water.

  3. To “get rid of” the rot, when doing a drain/fill, add about 0.5mL/L of bleach (yes, just regular bleach not scented or anything, Clorox plain) to the res as well, so about 4mL total.

I’ve used upwards of 5-10mL when it was really bad (during a “save”) though that was only for 6-8 hours and was outside of the grobo in a makeshift “ER”, basically a small bucket+air pump+humidifier in the corner on a table while I cleaned out the grobo reservoir with bleach (instead of vinegar) to re-sanitize.

That alone has helped considerably for me but I do not feel comfortable recommending that anyone actually tries this until I’ve seen it work through to the end. I saved my 3rd attempt this way after losing a 2nd one to root rot around 1 month mark; I tried hydroguard among many other things which just weren’t working in my environment. This last time I just said, “I’m going to try another solution from that other growing forum” and sure enough it has been more successful (and cheaper) than the recommendations here.

Your mileage may vary, I just hate to see other plants falling victim to root rot and the same recommendations being made which didn’t work in my case or were quite undesirable (like using a water chiller as that comes with a greater risk of flooding).

I had thought about buying Dutch Master Zone instead of Hydroguard for my environment, even though the latter is what everyone here recommends, because its magic ingredient is said to be chlorine and it is said to work when hydroguard didn’t.

Also - using hydrogen peroxide instead of bleach might seem to do the same thing, but for me it only lasted a week and then the root rot began to like it and took off like wildfire. I was re-applying it within 48 hrs and at first it seemed to be working, until it killed off enough of the beneficials that the bad bacteria used it as a launch pad (and food) for their next attack.

What I do is take a whiff (smell) of the water with the res lid cracked a bit, and if I notice the slight smell of chlorine is gone I re-apply another 4ml (roughly every 3-4 days, sometimes sooner). It dissipates from the water usually within 24h. Once you see that it’s in check, i.e. the rot is no longer growing and has basically “gone away”, just drop that dosing down to 2mL per drain/fill and it should stop it from reoccurring.

Another thing to note is that I haven’t yet started this from the get-go, i.e. from seed, so I don’t have good figures for how much to add and when for a new grow. I’ve only recently managed to save a couple plants using this method and will update this thread when I have more information.

I have recently switched to using pool-grade chlorine instead of bleach to eliminate the “extra stuff” (suspension material) that comes in bleach from being added to the reservoir; though from what I’ve heard and seen is no big deal anyways. I don’t recommend this to everyone, as this is much more concentrated than bleach and can be dangerous if not following the proper handling procedures. It was only $15 and should last me years if it works, though, so I’ll let you know how that goes after some more time has passed.

A cheap $20 pH pen (plus a calibration kit) is worth the investment as well, to at least double-check you’re in the right ballpark (pH/EC) when doing a fill. Everyone says to buy the expensive ones, but I haven’t yet - am holding off on the hopes that the grobo team exposes our data to us as I have two expensive ones already sitting in the reservoirs (as I own 2x grobo units)!

Also keep in mind that my intent is not to “cheap out”, but also not to over-invest where not necessary to. As others have outlined, some of us weighed the value of purchasing these devices (humiture module, ph/ec probes, atmel device to drive them, related switches/modules that go with that, etc) against the cost of a grobo and saw the grobo as “about twice as much, but we get it fully integrated”. I was sadly mistaken when I unboxed my grobo (more than 30 days after purchase due to being out of country) and set it up only to discover how closed this platform actually is! It was disgusting and disheartening to give an idea of how I felt that day, but I couldn’t send it back and basically had to make it work at that point.

My expectation when purchasing was that much of the data visualization and presentation that I would’ve had to develop (or setup from opensource examples) myself would be provided, i.e. “THAT” is what I expected from the app. Instead, it was the exact opposite with little to no data being displayed with that not-so-subtle boxed-in/proprietary feel. I fear for the longevity of the platform should another company step in with an API-first mentality and win over those such as myself who expected as much from this product.

The reason for outlining the expectations and deficiencies in the last part of this post, is that a lack of access to that data makes such experimentation (as described in first part of post) much riskier than it should be. The thought did cross my mind to write a script to send in a ticket to request my data from support once an hour, and to parse their response to put in my own database, but really?? I’m sure that’d get old rather quickly (and be subject to huge delays/gaps in data) and is not really something I’d actually do but does illustrate how painful it is to some of us “advanced” users, especially when posed with problems such as I’ve experienced.


Interesting read
Thanks for sharing.

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Glad somebody found it interesting :slight_smile:

I’d be ecstatic if I could get feedback from people as to the air quality in their home. Particularly, do you have a lot of dust? Also have you experienced root rot?

What I’m wondering is if there’s a direct correlation between dust and root rot, as I notice many of the successful growers pics don’t show any dust accumulating anywhere inside their grobos after 2+ months of growing (unless they’re wiping down their bottles, and even then I have been zooming in to check for any signs of dust!). I also notice this in the reservoir pics, I have stuff floating on the water level (not a lot, but the odd hair or two and dust/etc) but that doesn’t seem to be common to everyone.

I’ve thought about using pantyhose as a barrier to limit the dust intake, but that’s about where I am on that and am inclined not to restrict the airflow as that has been a separate issue.

Interested to hear if others with root rot issues also live in older buildings, or if those without root rot issues live in newer buildings (whether house or apartment). There is always dust floating everywhere in this condo and a friend of mine pointed out that could be why I’m getting hit so hard every time so quickly regardless of what I try.


I have experienced root rot and no there is no “visible” dust. Remember dust is particulate matter, and as such can’t be measured by conventional means.

Root rot is typically a symptom of warmer than usual water!! 72 degrees and up​:+1::heart::v:

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I am over-generalizing when I say root rot, I think. Pathogens that might attack the root zone in particular is a better description.

With the newer unit (in terms of manufacture) it was brown slime that started beneath the water, but this time I managed to actually stop it. Right before trying chlorine I used hydroguard and waited 10 days, and it just ate the hydroguard I think because there was white and brown slime all over everything (water stone looked like a big blob) and it really multiplied. This was originally using the 2mL/gallon hydroguard from cocopod to current, and then upping the dose of hydroguard and waiting 10 days (to be clear).

After it got out of hand, she started drooping really badly and something had to change. For this (2nd grobo) grow I had seemingly followed all the recommendations (except water chiller) in terms of sanitize, keep light out, don’t let external temps go over 75F (keep around 69-70F), double-check pH when drain/fill and switch to RO water etc etc. For every 1 thing that requires tuning or attention there’s at least 10-20 things you need to know that can affect the outcome, several of which are not forgiving to the novice until enough experience/knowledge is gained (from trying and failing repeatedly, basically).

This is where I basically stopped turning knobs (or adding safeguards/extra parameters) and tried to dial it back a bit, hence do nothing but add a bit of bleach and see what happens. The first part of that was to clean everything out starting with the roots. I’ve added the full timeline below with pics but this is where I stopped trying peroxide and moved to a bucket with brand new airstones, water, etc, and a high concentration of bleach in the water. I also wiped down the bottom of the stem and whole reservoir cover with nearly pure bleach to really make sure everything got sanitized (better than previously with just vinegar).

With the older unit it was immediate white slime above the water. I bought this one used and have no idea what the prior experience was like, and had only followed the tutorial to clean it with vinegar for disinfecting. I know now that after cleaning with vinegar, and rinsing, that doing one more pass with bleach to really disinfect is required to get rid of stuff that really wants to hang on.

So after I finished cleaning the slime from one unit I basically did the same to the other. Both are still growing from that without any further issues, though I’m only keeping it at bay and haven’t entirely eradicated the problem I’m sure. The top side of the root zone isn’t looking as good as the roots beneath the water, but the plant is winning so that’s enough to continue the experimentation to see what helps; i.e. at this point if they don’t die that’s good in of itself, but anything I can figure out to further bring them back is what my goal is for the remainder of the grow. I can literally see them being attacked on the top side as they try to make roots into the water. One managed to win and the roots are white, but the other can only maintain white roots beneath the water and about 90% of her attempts to get roots into the water seem to be blocked and go a yellowish brown stopping just above the water line.

I was adding room temp water that was 72-73F, which was the main part of the issue, for the past couple fills I’ve been chilling half of the water in the fridge which I believe to have helped considerably.

Here’s the timeline:

  • Roughly 10 days after sprout, already twisting and showing signs that it’s not growing correctly. Resisted looking at roots until now but needed to see if they’re covered in slime like the last ones were:

So far so good, used hydroguard from the very beginning and everything seems to be right. It was taking a small squirt of pH up/down and dispensing the other nutes as expected.

  • This was about 2 weeks later, so roughly week 3-4, the roots are white but they’re just not spreading out much… and I’m noticing twisting in the roots (the main strands) just as is happening above. There is growth but it’s struggling, and the leaves are starting to getting crispy and go brown rather quickly.

  • A week after that, this is basically what she looked like:

My AC wasn’t working very well (only keeping room at 73-75F) around this time and I was also tuning/improving things on that end, and I don’t have pics of it but down below was a nightmare to see - a lot of brown sludge all over everything. It went from being super-clear to “are the roots under all that slime somewhere? and where did my airstone go what’s that big blob?” seemingly within 1-2 days. I was so mad I just dumped half of a 800ml bottle of 3% pharmacy h2o2 into the res and went on with my life for a day while I thought about what my next course of action was going to be, as I had written her off as “another dead one” at this point.

  • Two days later I decided to try to clean her up and salvage whatever knowledge I could from this grow. That concentration of peroxide was awesome at killing everything off (of the roots and air stone) and just left a white sludge at the bottom to clean up afterward.

Also check out these blooms that formed, a sign that more than vinegar might be required for sanitization:

All of this white crap is partly filled with baddies just waiting to get back in. This is when I started looking for ways to just eliminate that “living reservoir” aspect altogether to get some data from that perspective. I took the lid off (with plant) and put it on top of another bucket with new air stones and a high bleach concentration in the water and basically waited to see what would happen. I also got a programmable humidifier (the one @Osage recommends, ty for that!)

Below the lid is a dollar store 1 gallon bucket filled with tap water and about 1/8th cup of bleach. The cocopod is touching the water line.

  • 14 hours later, already perking up - not a whole lot of light today:

  • 12 hours later, a lot more of the smaller leaves are starting to unfold back toward where they should be:

  • During all of that time I had cleaned out the grobo (following the instructions to letter again) but with bleach instead of vinegar. Then I put her back in later that night after nearly 2 days on the ER table:

this is the point at which I stopped adding new variables/changing others, and just continued refreshing the bleach in the res

  • 4 days later she’s stretching out, moreso than ever, and trying really hard to keep her leaves straight - probably in an attempt to avoid another trip to the table :laughing:

So the next day I trimmed off some of the dead weight:

And then I topped her when all was trimmed:

  • 3 days later, slowly-but-surely more of her leaves are starting to untwist themselves:

Also had the privilege of harvesting these tasty morsels that day (they are roughly 18 inches tall):

  • Shortly after that by a day or two, the two new stems start to make their appearance:

  • Another week went by, can see measured progress as she nears the height of the “top of the first fan” – a right of passage amongst grobo owners. Those who reach the second fan are sure to be enlightened. :rofl: Those two stems are taking off:

  • 5 days later still stretching, passed the first fan! Morning and evening pics:

  • 4 days later, one of the branches is really stretching - enough to start measuring if she’s reached the bottom of the top fan!!

Since the switch to bleach I’ve seen an improvement, but I need to try it from seed first as well as eliminate the bleach and see if simply cooling the water when drain/fill was the actual key to keeping it in check in my case. As stated originally, I don’t recommend anyone try this but am sharing my experience.

Here’s some pics of the roots, too:

  • About two weeks ago:

  • About a week ago:

I’ll take some new pics tomorrow to refresh this with, but there isn’t a whole lot of new root growth. Much of what starts white turns brown and kind of stops if it doesn’t reach the water. What’s in the water is slowly growing. I’m considering trying something like recharge in a future grow, but not until I’m certain the other parameters are in check first.

Oh, and I also added 2 air stones to each unit powered by two dual pumps. So one of the air stones in each of the grobos (in addition to the one that it comes with) is being powered by an alternate pump - if one pump dies each unit still has 2 air stones, if two pumps die they each have one, etc - bit of redundancy there as that seems to be one thing that’s sure to kill her if it goes out.


Those pics make it look a bit darker than it actually is due to the black res behind and the poor lighting, there’s no sludge or anything on the roots and they’re a bit yellow but not really brown (beneath the water). Above the water is fairly accurate from the photo, some white but mostly yellowish brown in color.

Here’s a root pic from my other grobo:

Lately more of these had shot down through into the water and was looking really good, will get better updated pics tomorrow. Up above is a different story:

This one looks a bit better today (not the above photo, it’s older), she’s stretching out more again, but already starting to flower it seems.

I’ll post about this grow separately another time, it’s been an interesting exercise in learning what the nute bottles actually bring to the table. :slight_smile:


((#Wow)): :astonished:

((#TheMoreYouKnow)): :wink::nerd_face:



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Here’s pics from today for the cheese auto, Day 64 (Flowering Day 5/31):

Can’t even tell where it was topped and the red highlights are pretty cool, too.

Roots are looking way better today, even some that had stopped appear to have started reaching again:

Here’s pics from today for the AKxCM, Day 45 (Transition Day 4/14):

And down below there’s signs of improvement as well:


Great save!

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Why not just fix the conditions that are giving you root rot? I really can’t understand the “but my apartment has dust” reason when I have a grobo making fat buds in my 90+ degree garage. I get having a chiller is undesirable, but you’re growing cannabis in a deep water culture.

You’ve got some issues with your grow setup, and you’re masking them by literally pouring bleach on it. You can get blood stains out of your sofa the same way, but why not find out where they came from first so you don’t get stabbed too?

I’m definitely not putting bleach into a plant that takes in nutrients and then gets combusted or vaporized into my lungs.


Nothing wrong with a water chiller either. Each tool has its reason for being. Since I’ve had my chiller, I’ve had no problems, and I can use it for my soil grows too if I decide to say fk it to hydro :joy::joy:


@Tito - a “reason” hasn’t really been zeroed in on yet (besides the water hit 72-73F), but dust is said to carry (a diverse set of) bacteria/fungi that varies quite significantly between different buildings, environments, and seasons. The curiosity I have is just whether this factor might play a (significant) role when trying to avoid root zone pathogens – you can see the dust collecting on my fans in pics, which I don’t see in many others’ grows. My wife has problems making sourdough since we moved here, which she also believes is due to a similar if not same factor.

This current combination has done more to keep the water clear after trying hydroguard and orca (but not dm zone). Pool grade chlorine was recently substituted for the bleach, and besides the few hours in 1000ppm solution to clean off the slime originally, the concentration being added to the reservoir equates to about 1-2ppm total which should flush out if it’s even still present in the plant (tap water is allowed to have more than this). At this level it’s actually considered a nutrient to some plants from what I’ve read; as it’s been used in tobacco grows for decades and for tomatoes as well (the latter of which we don’t smoke, so it gets processed differently, yeah).

This is not meant to be followed so much as inform anyone else who might have the same idea. This is what happened for me when I tried it.

What is boggling me is how your grobo isn’t just turning itself off over and over again – my light shuts off for 5 mins here and there if it gets too warm (in the 75-80F range). That’s a separate issue to the water temperature.

Putting it in the garage is not an option for me but that would be nice. Originally, for the first 4-5 weeks of my first grow, things were looking much different. That’s when a second unit was purchased (used) to get them growing on alternating schedules for more frequent harvests. Before I even had a chance to use the other unit the first one became infected.

Also noticed that you’re still on your first grow and the roots look pretty funky but she’s still growing strong and flowering. For one, you used a clone (not a seed) so that’s already a variable which could’ve played a part - the immunity from the mother/existing plant cells is my first thought but hormones also come to mind. Did you use any rooting powder or anything like that, any additives to water besides grobo nutrients? Trying from clone would be an option for me though it’s less choice on strain.


Here’s some pics from today, +1 day from the prior pics a reply or few above this post:

Here’s the other one:

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Fist ones not too happy at all. I’d feel the brown roots for slime. Second one looks better though

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Agreed first one doesn’t look 100%
The grobo powers off when over heats such as the fan breaking or blocked airflow or genersllybeing in a hot space.
I personally have had this bits in my reservoir which is typically parts of the plant that have died and broken off and end up sitting on the cover and potentially slip through the cracks under the cover into the reservoir. I try to remove these when I see them. I do agree with you that i think they need more than vinegar to clean but i think the trick is not nesc what you use but how well you clean it. Its tricky to get in some spots when your a giant human.

Grobo has never turned off on its own, and I have the Wattage meter to prove it. My roots look fine, not sure what you’re talking about. The only color they have is from the nutrients in the tank and big buds which commonly can stain them a bit. No slime, no smell. Clone was commercially bought in SoCal, rooted in rockwool and then transplanted to the coco pod. Chiller and hydroguard started 30 days in.

Your grow setup is producing issues and you’re using bleach because widely used methods aren’t working. Mine was the same way and I got a chiller and hydroguard from Amazon with no issues (and I keep my hydroguard on top of the grobo too).

Have you completed a grow and harvested? From what I can read, you’re still on your first grow too. Difference is I’m taking the advice of the pros on here and not trying to find a niche remedy to a problem until I try the others. Could be why I’m flowering :man_shrugging:.

I’m not posting my comments for you to heed, I’m leaving them here so other noobs don’t come and get ideas.


This is my 3rd or 4th attempt in grobo if counting both units. These grows aren’t as important since the outdoor grows were successful this year (measured in lbs), which is why I’m inclined to experiment with alternative (and inexpensive/low risk) methods in the grobos.

I did try several of the pro’s suggestions here, except for the water chiller. As mentioned, the intent is not to take the (increased) risk of waking up or coming home to water everywhere hence trying to find some combination that works before taking a more extreme measure. If this experiment doesn’t work the reservoirs are coming out and these will be soil boxes which was my original plan prior to coming across grobo advertising.

Once these are completed I’m going to do one with chlorine and one without and start to narrow things down further. Did cooling the water prior to introduction fix my issue, or was it the combo of that and chlorine? And then what other products might work as a safer alternative?

Too much additional cash and time has been invested to watch these die. Have bought equipment like fans and pH pens, cleaning/calibration kits, various additives and other products, different water, humidifier and countless hours of trying to diagnose the behavior and results. If the environmental constraints had been laid out prior to purchase there might’ve be a tent or supercloset in place of these grobos today.

Thank you for your input about additives - that’s helpful. I’ll reiterate – don’t do what I did here it is only meant to inform not to suggest anyone else tries it. At this point my first oz in the grobo will have costed quite a bit.


Sorry about your struggles! I have been dealing with humidity issues and I tried adding water that had been refrigerated over night and it brought the water temp down for a day and a half and then it went back up and has stayed that way for at least a month or longer. I have not added anything in my reservoir due to this. I can’t see any sign that the plant has been affected at all. You can see more details on my topic page of Kush ‘n’ Cookies. I too have a lot of dust in my house because my walls are made of Plaster of Paris but I have never seen any in my grobox even though I have a fan on top directed to the back of it where my wall is open/exposed. I live in Michigan and the weather is always changing. I hope this information can aid you in figuring out the issue and thanks for posting and being honest about your problems. We have to work together!

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I have been trying to use a 2-16 ounce frozen water bottles out of the freezer everyday one after the other. My H2O tempurature is now 69 degrees.

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