Need Some Input on Tank

Hello all, I have a few questions for you. First, I am currently running a 175 watt PFO fixture with a Blue Life S.P.S bulb. Is this sufficient for soft coral and my condy anemone over my 39 gallon tank? I figured it comes to about 4.85 watts per gallon. Second, I'm having problems maintaining the salinity in my tank because of the evaporation due to having to blow a fan across the surface to offset heat absorption from metal halide light. Is it a good or bad idea (in your opinion) to put a glass cover over? I've read that some people think it interferes with as exchange and causes water temp. to rise, while others like it becuase it helps with evaporation.I was thinking of covering the whole tank except for about 2 or 3 inches in the back to allow some fresh air to get in. Any help would be appreciated, thanks.

 

Salinity maintenance shouldn't be an issue from evaporation. The salinity will rise overall as the water evaporates, but will be restored to right where it was; after replenished with fresh topoff water. If the water is evaporating very quickly, then you'll have to topoff at least daily, but it shouldn't be drastic enough to have a detrimental effect on your inhabitants.

You might consider employing an auto topoff system (ATO). This will keep your salinity steady, while precluding the need for you to be carrying buckets of water.

As for the glass tops, I'm very biased against them. If you're going to have corals, the downside far outweighs the benefit of preventing evaporation. With lack of gasseous exchanges comes imbalances in O2 and CO2, favoring too much CO2--which will wreak serious havoc on your pH.

Again, look into an ATO. Evaporation is part of the game. Preventing it is usually not the way to go. Working with it will favor your tank's livestock.

 

As to your second question, yea or nay on a glass cover... IMHO the short answer is don't put a glass cover on there. Here's why:

• you are already concerned as to whether you're getting enough light into the tank. even a clean glass cover will dercrease the PAR transmitted to your tank
• I did have glass covers on my 125 a few years ago (ran 4 x 72" VHOs above it). not only will the glass itself decrease transmission but there is inevitable condensation on the the glass which further reduces PAR transmission.
• Worse yet, IME glass covers are begging to have some major salt creep issues on your cover. Still another factor in decreasing light to your tank and a PITA to keep clean.
• this is a bit circular but here goes... you want good light (don't we all) so you got MH's but now you pay the price in terms of heat in the tank. You have already hit upon the easy/cheap solution and that is blow a fan across the surface. The evaporation is a very effective way to remove heat from your tank but now you are annoyed by the amount of evaporation and the acompanying rise in S.G. Your question relates to how you can reduce the evaporative loss from your tank but if you decrease the evaporation, then you're back to the heat issue. Worse yet, you are considering a solution (glass cover) that will decreas your light transmission to atleast some degree and it was trying to increase your light that got this whole thing started.

Here are some tactics to consider:

• Keep the MH for your light, and decide whether you want to find a new cooling solution that will allow you to ditch the fans and decrease your evaporation or find another way to smooth out your S.G. fluctuations.
• I think the best answer for your situation is to invest in an ATO (automatic top off) solution. Unless you are a really ambitious DIYer this won't be free but it will almost certainly be a lot cheaper (both in terms of acquisition and electrical costs) than a more aggressive cooling solution like a chiller. It will also solve your problem with fluctuating salinity and decrease your overall maintenance.
• If you currently have problems with your tank overheating you could make the bigger investment in a chiller. This is certainly a nice thing to have if you can afford it and a big enough chiller could eliminate your need to run fans and rely on evaporative cooling.

 

ReefSparky beat me to it while is was typing. I guess that I've got to learn to type faster or write less.

 

Thanks for the input guys, truly. I was looking at chillers but they're too big for my budget at the moment. However, i'm considering purchasing an ATO. The one question I have regarding that is this: how do you "program" it to fill the tank to the correct level without going over? Is there a valve or other mechanism that does so?

 

It depends on what kind of ATO you get. Some use float valves and others use float switches but they all come with directions.

~Will.