Water Chiller Accessories

Ok, so I’ve decided to return my generic chinese water chiller. I’m going to go with the following chiller, as suggested by @Bplatinum9 and a couple of others:


That said, I have a few questions about the accessories I need to buy to make this optimal for Grobo use that I think would help other newbies as well and am hoping you guys can help:


  • What are the pros and cons on submersible vs external pumps?
  • Should I go for a higher rated flow just for future-proofing (like for when I outgrow the Grobo or add a second unit)? Or would it flow too quickly to cool the water? I was thinking of getting the Vivosun 800gph submersible pump as it’s the best seller and only $25. I know 800gph sounds like overkill, but I’m accounting for possible exaggeration of claims, and also hose size affecting flow.


  • Which size (inner diameter, outer diameter) would be optimal?
  • Are clear hoses fine? Do I need the black ones that block out light?
  • Does the material rigidity matter? Is soft or rigid best?
  • Will flow be affected if I were to run the hose upward with the chiller on a table?


  • Do I need them?

Misc.: Any other accessories I might need or pertinent info?

This is the link to the pump I mentioned btw:



i went with external pump sitting on floor next to chiller.

I went with 1/2” hose. No real strategy. Just what I have

One thing I did to make it easy to prime the pump is to put a T fitting and a valve on the pump output so that I can open the valve and pour water into the pump and down the input hose with a small funnel (Water flows all the way to the the grobo by lifting pump 1-2 feet off the ground). Then I close the valve and turn on the pump (see pic)


Thank you for the pic! Does that mean that using an external pump requires us to manually feed the unit water?

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No just that priming the pump to get water flowing can be a pain depending on where the pump is relative to your reservoir

For drain / fill I do this

  1. shut off pump
  2. drain in grobo app
  3. fill 2/3 and pause in grobo app
  4. turn on pump
  5. resume fill in grobo app

I’ve been hearing about “priming” on here, but don’t really understand what it means. Is your way of filling just a preference? I thought it was best to keep the chiller & pump off while draining and filling to avoid messing with EC + pH sensor readings and water level sensors? Or is your method specific to your pump / placement of pump?

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So in general a water pump wants to be full of water and ideally the hoses and the pump itself would be full of water before turning it on. Running a water pump with just air would eventually lead to damaging the pump. So the process of putting some water in the pump (and lines) is called ‘priming’. You would notice that if you just put the hose in the water and turn it on that it will take a while to start pumping (or like not at all). I’ve found generally that as long as there’s water in the pump and the end of the input hose is submerged then it will still pump even if there are pockets of air in the hose

The location of the pump relative to the reservoir determines how much work the pump has to do. Like if your pump was up 6ft from the reservoir it would be hard to pump. In my case the pump is on the floor so it only has to pump it up out of the reservoir. I’m not totally certain but I think the bigger climb up the water has the more water and less air you’d want in the pump/hose as it’s just another factor making it hard to get started. Usually if you look on a Package or instructions for a pump it would mention maximum height it can pump vs. diameter of hose.


Thanks so much for this explanation, I get it now :grin:

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Here’s a better picture of what I set up to assist in priming.

So I open valve, pour in water, close valve; turn on pump :wink:


Where do you live?

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Ontario canada


Ok makes sense. You also have the humidity naturally.

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basement setup tben or garage?

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Chiller is in furnace / water heater room which has the luxury of having a floor drain. Grobo is in another room the other side of that wall with the hoses running through a hole in the drywall.


Fair enough. And you need the chiller in the basement? Or just to improve quality of grows

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Got it, thank you!

I notice you have the inkbird controller attached to the chiller - is it necessary? Does the chiller not turn on & off on its own based on your set parameters?

Also, do you know your pump’s specs?

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Cool setup, wish I could do the same in my rental lol.


@Hellyesshedid The inkbird controller is for temperature for my germinating seeds in the same room. Just sitting on the chiller to keep it off the floor

@Todd.grobo depending on time of year and whatever the heat/AC is set to I find the water will still get up into the 70+ range. Haven’t had any root issues since I got the chiller. The plants love it.

@Hellyesshedid this is the pump model

Probably overkill.


Ive been hesitant in using my basement. I appreciate hearing that. Upstairs is definitely too hot these last 2 summers but shouldnt be.

Looks like I’m gonna be needing one myself.
My water temps got up to 77.8 today and I live in Michigan.
Good thing I use hydroguard! It doesn’t seem to be affecting my grow and I could only get it down to 77.0 with a fill today.
I use two small fans inside and I keep my home thermostat on 67.0 degrees.
I was able to fight the good fight for awhile but with summer approaching I’m just not looking forward to constantly monitoring water temps.
@Hellyesshedid I will eventually buy the same one I recommended to you along with a better pump so let me know how your doing when you get yours and I’ll do the same.