The right size chiller?

[TheGreek21]

Hi all, I have a 210g swim tank that without a chiller stays consistently at 80-81 degrees F. What size chiller would I need to keep the tank in the 78 range? For a tank this size, it recommends a 1/3hp chiller. I want to know since I only need to drop 3-4 degrees, could I get away with using a smaller chiller? Thank you!

[slief]

Hi all, I have a 210g swim tank that without a chiller stays consistently at 80-81 degrees F. What size chiller would I need to keep the tank in the 78 range? For a tank this size, it recommends a 1/3hp chiller. I want to know since I only need to drop 3-4 degrees, could I get away with using a smaller chiller? Thank you!

Anything smaller will run for a longer periods of time so a 1/3 would be about the smallest I’d go with that volume. But I’ve got to ask.. Why the need for 78? 80-81 is just fine for a reef tank or even fish tank. I used to keep mine at 78 and paid through the nose running my 1/2hp chiller 10-12 hours a day. About 9 years ago, I upgraded my equipment to reduce the heat transfer and now I just let it run its course. No chiller, no heaters. In the winter my tank hits as low as 75 and in the summer, it’s consistently running at 80-82. I have over 70 fish in my system and the display is packed wall to wall with thriving corals. My best growth is during the summer months when the tank is at its warmest temps. Best of all is that I haven’t run a chiller in 9 years. That said, you could probably accomlish the same thing using fans blowing across the waters surface. Evaporative cooling can be very effective. You would just need some sort of temperature controller to turn the fans on and off at your temp set points. Or depending on your equipment and house temps, a pump change or lighting change can result in dramatically lower water temps. This assuming you keep your house at temps at or below your target tank temps.

[TheGreek21]

Thank for your input Slief. So is 81-82 safe for fish. I don't know why but I've always had the assumption that 78 was the max temp. In that case, I might as well not waste hundreds on the chiller and electric involved.

[slief]

Thank for your input Slief. So is 81-82 safe for fish. I don't know why but I've always had the assumption that 78 was the max temp. In that case, I might as well not waste hundreds on the chiller and electric involved.

It’s perfectly fine in my experience. If it were me, I wouldn’t be worrying about those temps. The issue with higher temps is that dissolved oxygen gets lower as the temp increases however most of us run a lot of flow. If you have decent surface agitation and good flow, dissolved o2 should never be an issue at those temps. And like I said, a couple fans like the 8” clip on ones sold at walmart blowing across the water surface can do wonders for dropping temps a couple degrees or more.

[TheGreek21]

This is great to hear. I'll get a temp control unit and a fan and blow it over the sump. You saved me a lot of money. Thanks!

[slief]

This is great to hear. I'll get a temp control unit and a fan and blow it over the sump. You saved me a lot of money. Thanks!

Glad to help! Before buying a temp control unit, get a fan and test it to see how much of a drop you get. Since our sumps have a smaller surface area, blowing across the sump may be less effective but then again, you might be pleasantly surprised. Also, the higher the humidity the less effective evaporative cooling is so if your sump area is fully enclosed, the humidity will rise in that area and the fan will be less effective. So before buying a controller, I’d test with just a fan plugged into the way and monitor the temps for an hour or two and see what it does.

[tkeracer619]

81 is fine like slief stated but as spring approaches, depending on where you are located, you may want to address why the tank is running that hot. A fan across the top of the tank or sump as mentioned could do a considerable amount. Just pay attention as outside temps rise. IME 83 is the highest I consider safe under normal operation. My last tank swung 75 to 83 daily. Fans came on at 83 and chiller would kick on if tank hit 84. 85 is where o2 could become an issue and imo is riding too close to the danger zone for comfort.

I used a 1/4hp chiller on a 360gal but it wouldn't drop the temp, it would just keep it from going higher if the house was hot (crappy ac). My current tank needs almost 1000w of heater 24/7 to stay around 75.

What is running on your tank causing it to be around 81?

[EnderG60]

81 is fine, mine was hitting 84 in the summers for about 5 years before I broke down and got a chiller.

If you are going to get one, dont get the smallest one they say will work. Get a larger one. It will run less often and you will have some extra capacity should something go wrong and try and overheat the tank. If you still want one Id get a 1/2 or 3/4 hp.