new guy question on evaporation and covers/lids

Greetings all-

I've got a 100gal with an open top right now, with T5HO's suspended over the tank. I'm having a lot of issues with filling the tank, probably nearly a gallon a day, sometimes more sometimes less due to evaporation. I'm guessing it is due to the open top on the DT and the Sump, along with high flow rates through the tank.

My question - I've got the plans laid out for the pieces of acrylic to cover the open areas on the tank. Basically the only open area on the DT would be about a 5x5 area where the return goes into the DT, as well as a 4x8 area where the overflow sits. I figured I would need to do this at some point anyways to prevent any fish from escaping. I imagine this would also help reduce some of my daily evaporation woes. In the mean time... I'm researching some auto top off systems so I can actually leave town for more than a day and not worry about the pump running dry.

Any suggestions/confirmations would be appreciated!

 

I can comment on the the auto top-off & I’d like to hear from others as well, for my set up I use a Tsunami ATI system with a MaxiJet 1200. I keep a 5 gallon bucket full of water (one of the salt buckets) by the tank that feeds directly into one of the sump compartments. It’s been running this way for about a year now. The 5 gallons last about 5 days. When I go away I just use a 15 gallon Rubbermaid bucket in its place. This system works fine for me simply only because the sump allowed for it easily enough.

 

i loose about a gallon every 2-3 days on my 55 with a top (was about 1 every 1-2 without one). but i plan on using an ATO abd ditching the top in the future. its a pain to keep clean, block to much light. i will still use egg crate or soemthing for the jumpers.

 

An ATO system will be one of the best things you add to your tank. IMO, I would use a container, not run it right from your RO/DI unit just incase of a failure then, you will only have X amount of fresh water going in, not an unlimited supply. Second, the covers can be used, but keep in mind that this limits gas exchange. I would not add a cover to your sump and if you add a cover to your DT, I suggest doing what I did and drilling many small holes in it to aid with air flow. This will also help keep your tank from over heating.

 

Thanks for the replies, everyone. Great info

My RO/DI unit is in the garage, so I could run that w/ some float switches to the tank room and hide a 10gal rubbermaid in the stand perhaps.

Sounds like a good project....

As for the cover, I'll probably put on the cover for the top and rely on the oxygen to be delivered through the sump. There's about a billion bubbles in there from the skimmer and from the way i designed my return, so i know its getting plenty of oxygen... just hope its getting disolved well enough.

 

Air bubbles, even with a skimmer, do not significantly promote gas exchange. The bubbles of any size have a surface tension that resists this.
The way bubbles DO help is if they are in a tank and promote surface agitation where the air is in contact with the water's surface. However, that can lead to salt creep so it's best to provide the agitation with something else like a power head.
If you cover the tank, expect the pH to drop significantly over the next few weeks, probably at least point three or more, with the actual variation being affected by the CO2 levels in the home and the amount of airflow over the water's surface, and the CO2 production of the tank itself.
This is especially problematic in weather that forces us to shut up the homes so our CO2 levels increase in the home, making the gas exchange much more difficult.
High CO2 levels in the tank lower the pH.

 

Evaporation and surface agitation is a good thing. I doubt you have enough surface area in your sump to support the oxygen transfer your system needs. Leave it open top and let it breathe. My 100G evaporates as much as 3 gallons per day in dry months and an ATO is a must.