So of my experiences with water chillers for large hydroponics systems.
I have a larger than average NFT hydroponics setup and I wanted to share some info about various water chillers I have used.
I have 3 NFT systems in 2 greenhouses in a very hot climate. Today was 108F outside and just under 90 in the greenhouses. I try to keep my water temps below 75F but preferably under 70F
My largest system is about 800 feet of gutters, I've used 4 different water chillers.
First chiller was a 1/3 HP chiller from Amazon. It cost about $450 USD and was pretty much worthless. It wouldn't even run when air temps were over 90F
I moved on to Vevor 1.5HP chillers. The Vevor chillers could keep the water below 75F about 75% of the time. During the hottest parts of the day the temps would sometimes hit about 80F These chillers would pull about 1000 to 1200 watts, depending on the ambient air temps. At the time I paid about $850 USD for them.
I tried a 18000 BTU pool heater that could also chill the water. Chilling BTU is not listed but probably no more than half the heating BTU. On its own it was almost as good as the Vevor and pulled about 900 watts. When ran in parallel with the Vevor chiller it was about to keep the water around 73F during the time when the water would have been 80F with just the Vevor. I paid about $540 USD. I wasn't expecting it to do as well as it did for the price. I mainly wanted it for heating the water during winter.
Encouraged by the results of the small pool heater, I bought a larger Aquastrong pool heater/chiller. On its own it is able to keep my largest system under 74F all day long. It is a inverter heat pump and the wattage varies. During the hottest part of the day it pulls about 750 watts and goes as low as 350 watts as it gets cooler. I paid $1039 USD for it.
A couple of things to keep in mind for the pool heaters/chillers is that you make sure it pick one that is rated for "salt water pools" These units will have titanium heat ex-changers that will not corrode. Also both of the ones I tried have a water flow switch and need a MUCH higher water flow rate or they wont turn on.
TLDR Pool heaters / chillers work great with hydroponics.