Temp Control

[Tanked]

All my water parameters are perfect.My tank is 18 mouths old.I am still losing fish too ick.My corals are doing great, but in the night my tank temp still drops too low.I think a drop of 3 degress or less is ok.I have a good heater in the sump I have made several adjust too try to keep the temp at the 3 degrees or less line, but the temp still seems to drop 4-6 degress on me in the night .I think the 4-6 degress is to low and I think this is my problem .Is there any ideas on how to control my temp,or do I need to buy a better heater or do I need 2 heaters .The one I run now is a Visa-therm 300w.Is this too small for my 75g? Do I need to put a heater in the tank and the sump?The sump is 20g for a total of about 90g.Any help would be nice so I can enjoy my fish and stop buring them.

[perpetual98]

Maybe the problem is that your lights are warming the tank too much. Maybe try some fans or something to cool the lights and bump the heater up a degree or two. Short of getting a dual-stage temperature controller, you need to find a way to figure out what is causing the swings.

[at]

I would definitly put 2 heaters in your sump. One I would set about 79 or so and the other just slightly less 77-76 . That way if something goes wrong there is a backup just in case, especially if you live in the north. I think 2 200 watt heaters should be fine. I am surprised your 300 watt can`t maintain a5 degree temp swing.

[RWalston]

It may not be that the heater can not control the temperature of the tank volume. It may be that the heater itself has a wide range of fluctuation in the temp controller. some heaters have a +/- 2 oF others have +/- 5. Using a temperature controller will fix the problem

[Randy-L]

Could it be the flow is the problem? If the display tank is lossing heat faster than the warmed up water from the sump can replace.

Just a thought.

[Randy-L]

e more I think about the more I think I'm right. With the heater in the sump set to the temp you want the water returning to the display tamk will be at that tempurature and not hot enough to make up the diferance.

[dakar]

What is your turnover rate between the sump and tank? Good thinking that could very well be the problem.

[RWalston]

Not sure about that. The over all flow through the sump is a factor. I have a 300w heater in a 30 gallon sump for a 110 gallon tank. The return pump for the display is a Mag 9.5. The heater is controlled by a Medusa dual stage temp controller. The temp probe is located in the first compartment of the sump were the water enters the sump. The heater is in the last compartment before the water enters the main display. My temp controller is measuring the water as it enters the sump and is set at 80.5 oF. The temp controller keeps the heater on until the water temp is 80.5 +/- 0.8 oF(heater turns on at 79.7 oF and stays on untill the water is 81.0 oF. Setting the temp. higher on the heater will raise the temp of the water. If you have to set your heater at say 95 oF to get a tank temp of 80.5 then the heater is to small for the tank, the temp controller in the heater has a +/- oF do large, are the flow through the sump is very inadequate. Thus a 300w heater on a 75 gallon tank and a 20 gallon sump is adequate. So what remains is the flow rate through the sump and the +/- of the heater. Do you agree.

[perpetual98]

Check your heater after lights are out for a while. If it's on all night, then the heater is probably too small. If it's cycling on and off, then it's probably set too low (I never trust the numbers on the heater) and you can bump it up. I'm still thinking the heater is set too low and there isn't adequate cooling of the hood.

[RWalston]

That theory only works if he set the heater to the proper temp he wants when the lights were on say mh on for 6 hours around noon on a Saturday when he installed the heater. mh go off temp drops 10 oF. Most I say most people adjust the heater with the lights off. (day 1 Install heater, set temp to 80,day 2 monitor temp readjust temp if needed, day 3 monitor temp final adjustment if needed.) The heater is only there to compestate for the loss of temp at night when the lights go out. If the temp with lights are on is 82 and when they are off it is 80 then what perpetual claims is acurate. but no ventilation in the hood has nothing to do with the heater. that would be more of a chiller problem