Keeping Reservoir temps down

Planning my first rdwc system. Have two 2x2 tents that I planned on utilizing. I was going to use one for the grow pot and the other to house the reservoir and all pumps etc. I am in arizona and obviously summers get hot and I am thinking of ideas to get the res temps down. Given this is a small home grow I didn’t want to shell out the $300+ for a proper water chiller.

So while thinking of ideas I wanted to throw this out there as I have no idea if it will work. I have an unused mini fridge, would it move the needle on temps if I put the air pump inside the cold mini fridge and pumped cold air to the air stones in the tanks? Again no idea if this would work but throwing it out to get opinions.


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I’m not a hydro grower but I have read where some growers put frozen water bottles in there buckets.

Yea read the same. Looking for a bit more stable solution. Water bottles would seem to be high maintenance, fluctuating water temps and brings the possibility of water contaminates.

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Wouldn’t hurt but I doubt you would notice the difference. Will the grow be in an air conditioned space? I blocked off a corner of a shed, insulated it and got a portable air conditioner to keep the summer heat out of a 60 SQ FT area. I quickly found that a tent just holds the heat in (good in winter, bad in summer) The water will be close to room air temp. The A/C keeps it below 80 F on the hottest days in the deep south. I use aquarium heaters in cold weather.

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If your going to grow sterile, i assume your inside and will have the A/C on. That should be ok with good ventilation as long as you stay sterile “or try”. Your biggest challenge without a chiller is going to be stuff growing in the pots you dont want, and its harder to control without one. Brown algae that doest need light, loves nutes, oxygen, and sticks to everything was my nemesis. Clings to roots and suffocates them. Them the cyanobacteria starts. Covers your airstones and basically everything where nutes are. I went overkill, but i dont have time to switch the resivor once a week or every 4 days + argueably the nutes cost more than the chiller. Example is i dont need to change mine unless there is a problem @ 110 gallons i dump about $200 plus in the tank every res change with most food at 8 ml per gallon, i use almost a liter. With the chiller, and good filtration you can replace lost water with weaker plant food mix and not change it untill you have replaced the entire volume. So for me i would have to add another 110 gallons of 1/2 strength food mix before a change, or the food mix changes with the plant phases. Cut plant food waste WAY WAY down.

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What about putting a metal tube coil in the mini fridge and pump grow water thru it.

@Ricochet im following, i think that your on the right track, what if you had an old motor cycle radiator around or chep from junk yard. Pumping water through that inside mini fridge may give you the surface area you need to cool the water, or a hella lot of copper or other highly condutive metal. Whatever works, the amount of total water your keeping cool and how insulated said container is will dictate the efficency and size of the cooling system… i insulated mine with water heater insulation with glue…

Has anyone tried freezing balanced or pHed water? Might handle both temp and pH drift?

Ive never tried that, but it should. I add phed water/food back to my hydro system for that reason of ph drift / maintaining PPMs.

J3 here…can anyone tell me what the water temp should b in my hydro buckets

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It should be between 65-72* F :+1:t2::v::sunglasses:

J3…thank you