Using undersized heaters

O.K. right off the bat I will tell you it's not an aquarium as some of you already know. 330 gallon RAS (recirculating aquaculture system) which consists of a RBC (rotating biological contact filter) and a 55 gallon clarifier consisting of siphon and drum. Anyway I've presently got about 1000 bluegill fry 3/4 inch to 1 1/4 inch in the stock tank. It's in the basement and it's really tough to get the water temp above 62. F. The system was cycled before I put the fish in.

Anyway, my goal is to grow them as rapidly as possible while feeding them commerical feed. They are feeding well but as many of you know 62 F. is not optimum growth temp for bluegills. I'm planning on purchasing an 1800 watt submersible heater, but just don't have the moolah yet. A friend had a couple of 300 water glass aquarium heaters laying around and wanted me to try them. In 24 hrs. tank and clarifier temp has gone from 61.7 F. to 67. F. Kind of suprised actually.

I hope you guys don't mind it's not an aquarium but I was hoping some of you have expertise with aquarium heaters even though most natives don't need warm water.

Question # 1: Since these are undersized for the tank and they will probably be running full bore, will their lifespan be less than if they turned on and off?

Question # 2: Is there any danger of a electrical problems with them working so hard?

Edited by az9, 24 February 2010 - 10:12 PM.

No question running non-stop will shorten its life span. If they're good heaters they should last long enough to get a bigger one and/or spring comes.
I'm no electrician so anything I say should not be taken as the last word. There's no reason the heaters would be a problem as long as you don't have it plugged into an extension cord rated for 15 amps with a fridgerator, AC and the washer/dryer. Those skinny extension cords get hot.
I have felt a jolt or two from glass heaters that cracked and H2O got inside. Had one melt through a trash can when the H2O it contained accidentally siphoned out.

I frequent Monster Fish Keeper forums and it is common practice for people with larger tanks (200 gal +) to run several smaller heaters instead of a single large one. Reason being is that if a single large heater fails, either staying on too long or not working at all the tank temp does not swing to much.

I think that one heater may be more efficient, but if the thermostat does stick, either the tank is to hot or to cold.

I agree. And while it is common for folks to have multiple heaters in tanks, they must all be set to at the exact same temperature. I question the accuracy of the temperature knobs for the cut-off temp. These must be synchronized with each other if you have multiple heaters b/c even if one is set a degree or two above the rest, it will be doing all the work - unless temp decreases enough for the others to kick on.

Multiple heaters is preferable in low or no flow situations such as plant tank. My big plant tank with one heater and no filter would have very distinct cold zones, especially down near the bottom. Thick rooted plants prevented any water movement in the thicket. I never saw the mollies avoid any place or show stress but I could really feel it with my hand.

I agree. And while it is common for folks to have multiple heaters in tanks, they must all be set to at the exact same temperature. I question the accuracy of the temperature knobs for the cut-off temp. These must be synchronized with each other if you have multiple heaters b/c even if one is set a degree or two above the rest, it will be doing all the work - unless temp decreases enough for the others to kick on.

Thank you all for your replies.

As far as accuracy UncleWillie, I'm not that concerned with that as I doubt the temps will be able to go much above the low 70's even the heaters set at max temp of I believe it's 86 F. Just too much water and the ambient air temps is in the low sixties. But I could be wrong as I'm really surprised at how quickly the temp rose in 24 hours. It's now at 68 F, but nitrites seem to be creeping up so I'm doing a water change daily now and backing off on the feeding until things stabilize. Ammonia is fine however.

Edited by az9, 25 February 2010 - 09:02 PM.

Cecil,

Are you making any effort to trap air over tanks / system, especially the RBC? Most of your heat loss is from evaporative cooling once you start heating the system. I have also realized benefits of wrapping tanks with the insulation that is aluminum foil covered bubble wrap.

Jim

Thank you all for your replies.

As far as accuracy UncleWillie, I'm not that concerned with that as I doubt the temps will be able to go much above the low 70's even the heaters set at max temp of I believe it's 86 F. Just too much water and the ambient air temps is in the low sixties. But I could be wrong as I'm really surprised at how quickly the temp rose in 24 hours. It's now at 68 F, but nitrites seem to be creeping up so I'm doing a water change daily now and backing off on the feeding until things stabilize. Ammonia is fine however.

I hope to cover part of the tank once I purchase the other tank to move the RBC to. I also want to insulate the tank as you say but money is a problem right now. Man I'm telling you being self employed right now in this economy is the pits. If it wasn't for my wife's income we'd be in deep doodoo.

Edited by az9, 27 February 2010 - 11:17 PM.

The economy is why I am trying to use more insulation, less energy and fewer / smaller heaters. I am being told to make ready for deep budget cuts. Therefore, we are trying to figure out how to use less energy for heating, otherwise we will have to greatly reduce winter time activity. Problems of heating and its costs are not yours alone.