I am moving from a 5 gal DWC (using frozen water bottles) to a 17 gal set up and will require a water chiller. Tent air runs about 83 @ hottest. Water temp runs about 75. Which do I need to focus on more? GPH, BTU,WATT?
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Welcome to the forum, unfortunately all i know about them is that they are really expensive 
I chose autopots over rdwc because of heat and the entire Autopots system was cheaper then the water chiller alone 
Lets see if i can’t get you someone thst may be able to help you out.
@Nicky what you know about water chillers my freind 
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LOL sooo true!
In an RDWC system, you will want the entire volume of water to change once every 1 to 2 hours. The simple formula is the ( total number of gallons of water) divided by 2 (hours) = necessary GPH pump. Some prefer to divide by 1.5 because for a little more volume exchanged.
Ensure your meeting your GPH requirements of course, 83 is a little high 79 is what you should be aiming for. Is your duct fan not powerful enough? Or is it not an AC infinity thus no controller to tell itself to ramp up?
You’ll want to insulate everything and ensure there is white or reflective surfaces on all containers and hoses. Place your reservoir and your chiller outside of your tent as well.
83 is the hottest but only lasts like that for about an hour and a half during the day. Not an infinity sadly. Have it dialed all the way up. Using Vivosun VS2000 Light in a 3’x3x’6’ tent Thank you for all the help! Will also check into the autopots also.
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Would this be suitable to get the water to average around the proper temp or would it need to be bigger/smaller for the 17 gal?
SEAAN Aquarium Water Chiller Cooler Warmer with Pump 50-104 °F Temperature Setting Suitable for 16gal Water for Home Aquarium Fish Shrimp Coral Jellyfish 200-300 L/H (60L Chiller & Heater)
I think what you’d be looking for is the 1/10 HP compressor models of chillers. I don’t think you’d have much success with any of the Peltier designs. You’ll also have to figure in heat from your circulating pump. That adds quite a bit of heat too, even little ones… and that bit you hear about inline pumps not heating water isn’t accurate, at least not from the tests I’ve ran.
Even an inline pump will bring my water temps up several degrees overnight without any lights on. Any insulating you do to your buckets and lines just keeps the pump heat in, instead of letting the buckets cool off at night, so watch out for that too.
Water chilling is one of the trickiest environmentals I’ve tried to harness, and is probably why most people seem to settle on just plunking down a wad of cash for expensive compressor units that fail in a couple years and are non-rechargeable.
There are workarounds, like a bare basement floor that acts as a heatsink for the buckets, or some DIY concoctions utilizing used water coolers, A/C units, dorm fridges, etc. I’ve recently begun using a mini RV type portable chest fridge, filled with water to run a 25 foot line of vinyl tube through, but it’s kind of a specialty build that I haven’t seen specifically before.
There are some forumulas out there for factoring BTU loss in water chillers, but the options to pick a product from the results you obtain are still pretty limited, mostly to the 1/10 HP range, stepping up to a 1/4 HP next, but that seems large for your system based on my research.
EDIT: A quick internet search turned up this page with some BTU calculation info if you were interested in researching that aspect further.
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Hell, getting more complicated as we go lol. Was thinking about running a water pump through a coil in a cooler filled with ice back into the dwc.
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Personal bias towards build quality aside, that one appears to have an aluminum core, which you do NOT want for hydro.
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Precisely the principle I’m employing right now. Only I’m using the mini RV chest fridge filled with water I mentioned… and with this I do insulate my buckets and it keeps up with the heat fairly well. You’d want to get an inkbird controller to control the circulating pump to keep accurate temps. The 308s model is what I just picked up, which differs from the 308 in that it has a submersible probe.
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Thanks a ton!
Hope you figure out something good! I’m just using vinyl hose to run through the water, which is horribly inefficient, but it’s getting the job done. I contemplated a stainless steel wort chiller coil, but there’s always the metal interaction with the hydro salts, and the worry of keeping all that tubing cleaned out from water nasties. Vinyl hose is cheap to toss and replace once cleaning is no longer effective. This is what I cobbled together. There’s a small circulating pump in the 8 gal hooked up to a timer to stir the water every few hours. I keep it at the highest 50 degree setting and it doesn’t run any more than it did when it was holding beers 
I’m only chilling about 9 gallons with it, but so far so good with a 400w light in an 80 degree 2x4 tent. The main circulating pump runs about half the time during the day, but I can always lower the fridge temps for colder water.
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Just re-reading some posts over morning coffee, and thought I’d point out a major difference between this plan and the one I’m implementing with chilled water.
Depending on humidity, etc., water transfers heat over 20x better than just air. So for your example, the cooler filled with ice, should actually be ice-water to be really effective. You could swap out frozen bottles from the cooler of water, and keep the hose in the water to really get that heat sucked out of the nute solution inside the tubing.
This will get old really quickly and you won’t be able to leave your cooler for more than a single day… Sucks come a long weekend when you want to get out of town or something
Yeah, it doesn’t sound like a picnic, but if somebody’s already doing it and doesn’t seem to mind, who am I to judge?
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