abcha0s' 300G Ultimate Reef

[abcha0s]

Originally Posted by Delphinus

How much turnover do you have in your sump compared to tank volume? I've always heard the general rule of thumb that you need around 5 to 7 times volume turnover through the sump to keep heaters down there. I'm sure you have this or knew it already but it bears asking.

What's the ambient temperature in your house? All things being equal your tank should equalize to that after some time and you would only need to heat your tank the incremental difference. Ie., house at 21c the heaters need only raise it 5c to get to 26c (sorry I don't think in terms of F for temperature. The very first dive I ever did was at the Great Barrier Reef, the water temp there was 26c, and that's what stuck in my head mentally ever since). If you run your house at say a chillier 18c the heaters need only bump it 8c to get to 26c. That's not a lot.

So I'm thinking that either the heaters aren't outputting what you think, or there is loss of heat to somewhere (the floor? is the sump sitting directly on concrete or is there foam under the glass?)

If all 4 heaters were on that should be the full 1200w which seems ample to me. By contrast, my 280g, I use one 1000W titanium heater on a Ranco controller, the RO/DI was a frigid 8c filling up, and the heater brought it to 26c within 24 hours (not sure exactly how many hours it took, I just checked the next day and it was 26c). It's been steady ever since. So I think your 1200W should be doing the trick, there is something more going on here that we haven't put our finger on methinks.

Thanks for the feedback Tony

I have almost exactly 4X turnover through the sump (300G total water volume - 1200Gph measured return). I had never heard the 5-7X guideline before, but it is interesting though. I'm sure it has to do with the rate of mixing and the temperature variance between the display and the sump. More turnover would reduce this variance, but heating the water in the sump to a higher temp should also counter this effect.

Ambient house temp is ~20C. 78F converts to 25.6C, so our targets are similar enough. The heaters have to provide ~6C of additional heat.

We have our furnace thermostat set to lower the temp during the day while we are at work and at night while we are sleeping. I think I will have to consider the effectiveness of this strategy.

I'm interested in the titanium heaters. I've read that they are more efficient watt for watt than traditional glass heaters. By the sounds of it, they may be considerably more efficient. I'm not getting anywhere near that much heating power from my heaters. They aren't exactly expensive either, so I will probably cut my losses and go in that direction.

As you suggested, it's likely a combination of factors. I'm still working out the bugs but I'm getting really close to adding the first fish!