Rusty leaves

I’m seeing something similar on my first grobo grow. We are in day 16 and it’s a cheese Auto from canuk. I measured the pH to be around 6.3-6.4

Just did a water change 3 days ago and the spots turned from greyish brown to rust colored since.

Should I grab some of this cal/mag?


Your nutrients already have cal mag in them you really should wait for support to just adjust your nutrients I think.


Good to know… thanks @Bplatinum9 how do you know what is in each of the 5 grobo bottles. I wonder sometimes what would I do if grobo nut kits were suddenly unavailable. Can I mix my own?

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You can mix your own if you were offline and didnt use drain and fill etc…
Other nutrients were not formulated for Grobos Probes, sensors, drains, etc… It could break/clog your system.


More very valuable info… thanks @Bplatinum9


Bottle(1) Basic: to increase your plants ph level works with bottle (2) to make sure its balanced and your plant is healthy.

Bottle(2) Acidic: used to reduce your plants ph level.

Bottle(3) Micro: Gives your plant the tasty nutrients that they need to blossom from a tiny seedling into a big beautiful plant that’s ready to harvest.

Bottle(4) Macro: Nobody likes being hungry and your plant is no different, (3) & (4) work together to keep your plant feed.

Bottle(5) Balanced: balances and primes your water to help your plants thrive. Brings your water to the perfect state to grow in if your using distilled or Reverse Osmosis water.


Cal mag issue. Please add cal mag


@Bplatinum9 is saying there is already cal mag in the nutrients that come with the grobo.


You add more cal-mag in, you risk worsening the situation.

Since you cant see your data - Your at the whim of Grobo.

I have a Blue Labs PH and Conductivity Pen for situations like this. Just a shame, because the Grobo already has these sensors, we just cant see it.


I have both a pH and ec pen. Teach me


@Osage, is as experienced as it gets and his advice is solid, he would know what and how to add but you will still need to know why this has happened on top of the experience he possess.
Its like going from 4 to a 10 without understanding the whole picture.
So yes his advice will always be correct and if your confident in what your doing he has the best advice!
Lord knows I have followed him without question.


@Osage are you suggesting I add cal mag myself or wait for grobo support? Would that require a water change or just ad it. I just did a water change 3 days ago. Also should I add a full recommended dosage or less considering grobo nutes

Keep in mind if you add cal mag yourself, the ph will still be off on your machine unless you want to keep adding cal mag every week.
And if your going to get the ph adjusted by support and then add cal mag I think its possible it will throw the ph off again.

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Understood. I was talking to the guy in the local hydro store. He asked if I was using RO water and when I said yes, he was the third person to say that’s why. He sold me on this boogie blue filter that is faster than RO and just removes chlorine and floride. He said he switched to this so he didn’t have to mess with cal mag… thoughts? I bought one and am thinking about just doing a water change

The grobo determines whether or not to use bottle #5 (the cal/mag) based on the EC/PPM (TDS) of the water at the time of filling. If it looks like it is distilled or tap water (the EC/PPM is greater than some value) it will not dispense from bottle #5.

The one thing you’ll definitely find prevalent in most advice here is that it almost always depends on your specific environment to some extent. You can tune for RO water, or tune for tap water, or tune for somewhere inbetween… finding “what works for you” is a big part of the battle.

Your tap water (and what does or doesn’t get filtered) is an immediate example of that; there can be iron and other elements that will vary from one water source to another which in some cases can invalidate perfectly good advice (worked in one area but not another). I tried a handful of sources until I just settled on one and kept that parameter constant to dial in others. If she’s been drinking the water and growing up to this point there’s probably not any problem with the water so much as the level of cal/mag she requires.

I’ve found with DWC that things seem to manifest quickly, but can also be resolved as quickly. Waiting the weekend for a response might seem like an eternity but once corrective action is taken it won’t be long until you see the results. If you still see new growth occurring (topmost leaves getting bigger) and she isn’t curling into a ball then it’s not really cause for major concern yet.

FYI If you have a dropper or something you could add a few mL (literally; 1-3mL) of bottle #5 as a means to add cal/mag.


So I started off with distilled and then with tap through an RO filter on my last water change. Funny you should mention bottle 5 as it seems that the grobo has consumed more from 5 than any other bottle. I’m going to wait for support but I think I’m going to stay away from RO water from now on… either distilled or going to try the Boogie Blue garden hose filtered water for my do so dos seed. @vegetato thoughts on the boogie blue?

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I’ve been loving my Distilled Water Maker - No problem on my grows for sometime, and no more store trips getting distilled water, or replacing filters for RO.

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@liddellOnus - that filter is interesting but does state in the advertising that it only eliminates ‘most’ of the chlorine (with each more expensive filter doing a better job than the lesser). If you already have an RO system it’s likely doing a better job at that. That’s an important point to note if using hydroguard or any beneficial bacteria, so it doesn’t get killed off automatically by the water itself. If you’re not using hydroguard or mycos (think recharge) it’d probably be fine.

I believe this filter is better used in outdoor and soil gardening than in water destined for a DWC reservoir; though if running a “sterile res” it’d suit the purpose though might not be as good as distilled or RO if there are other minerals/elements present (back to the prior point - composition of water from one area to another). When using that filter outside there’s a (better) chance that most of the beneficial bacteria will survive as most of the chlorine has been eliminated, but when the beneficial bacteria have to live in that water that’s another use case entirely.

@shadowcipher89, I had the exact same experience here (after purchasing distilled water maker) – mine has a tea bag sized carbon filter to change every 2-3 months but it came with enough spares for a year or so. I was buying 6x4L every week (so about $12/wk, or $50/month) and this unit only cost $89 so it’s definitely been a good investment from that standpoint too. There hasn’t been much of a difference in terms of TDS/PPM readings between the storebought and self-distilled, but that’s ignoring the fact that I have no idea what the last 25 PPM actually consists of. :wink:

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How long does the distiller take… I assume hours

I live in Massachusetts. Apparently we have some really good water. I have an RO filtration system but from what I gather, the plant needs some of the things it removes like iron and calcium.