Evaporation

[Kurt_Nelson]

I top off twice as much per day during July/August than I do the rest of the year.

For me, most of it is because the hot months are when I run the clip on fan to keep the temps down. The clip on fan alone will cause a huge increase in the evaporation rate - which makes sense because that's how it cools things down. Evaporation takes energy, and that energy loss is what helps bring down the temp of the tank.

For other folks, it could be air conditioning. A/C will dry out the air, and drier air will allow for quicker evaporation.

[lance]

First i must say you dont want to cover your tank. You need good air flow above the surface for proper gas exchange. This is your O2 source as Salt water fish get there oxygen from the water and from saturated oxygen not from air bubbles large enough to see. Then your best bio filters , the LR and LS will convert ammonia and nitrate into nitrogen then released at the surface but if your tank is covered then your O2 is low and bio filters cant work as it should.

Then evap. is normal , my 75 evaps around 6 gallons a week. I use a doser and 5 gallon jug to keep it topped off. But keeping it around the same level is best. As it evaps then salinity changes and in a smaller tank can change fast and the constant up and down isnt wanted. In fact the top off unit is a very easy DIY and help reduce time of maintaining and increase time for viewing.

[Ziggy953]

I'm with Cmor...I top off about 3g a day. RO/DI with an ATO makes life much easier.

[catmel]

Originally Posted by lance

First i must say you dont want to cover your tank. You need good air flow above the surface for proper gas exchange. This is your O2 source as Salt water fish get there oxygen from the water and from saturated oxygen not from air bubbles large enough to see. Then your best bio filters , the LR and LS will convert ammonia and nitrate into nitrogen then released at the surface but if your tank is covered then your O2 is low and bio filters cant work as it should.

Then evap. is normal , my 75 evaps around 6 gallons a week. I use a doser and 5 gallon jug to keep it topped off. But keeping it around the same level is best. As it evaps then salinity changes and in a smaller tank can change fast and the constant up and down isnt wanted. In fact the top off unit is a very easy DIY and help reduce time of maintaining and increase time for viewing.

Oh I know I try to keep the 'doors' on the top open when I am home, otherwise I keep them closed due to my very curious cats, I dont want expensive sushi for them lol. There is a good amount of open space in the back, where it is cut out for the filter and skimmer. I know its not the best, but I'm working on it As of right now, I only have one 1" clown in there right now. I'm looking into getting a better lighting system, when I do I'm going to put eggcrate or wire over the top then.

thanks for the help on the evaporation issue.

[lance]

If yo have only a fish or 2 then they might recieve enough O2 but as they grow and you add more stock then your water O2 saturation will be very important. And covering the top just wont do it.
If you want use an eggcrate type material to cover. This allows good gas exchange with some security.

You cant cover your salt water aquarium as this gas exchange is vital to its health.

[ryshark]

Catmel, that 40watt light fixture you have is probably fine while you only have fowlr. The fish don't need a whole lot of light. Now if you want your tank to be brighter or you want to turn it into a reef, that is a different story. Then you would need to upgrade. Personally, I would save my money on the lighting upgrade for when you are ready to get coral.

[Kurt_Nelson]

Originally Posted by catmel

...There is a good amount of open space in the back, where it is cut out for the filter and skimmer. ...

With all that open space in the back, I wouldn't consider this covered then. If you end up having a low pH issue though, you might reconsider.

Sounds like the same type of setup I have, except my two glass pieces are suspended on shelf sliders (the front portion slides under the back portion... it doesn't hinge) so there's some air gap between them also. I've never had pH or O2 issues.

[catmel]

thanks kurt + ryshark. Its a typical top, with glass under where the one strip light sits, plus two small 'doors' at the very front of the tank that cover the front. They're propped open a bit from the cord for the powerheads as well. Also like I said before, has a big space cut out in the back for the skimmer and filter. I've had no problems with PH or o2 saturation.. ph is 8.2 and has been since setting up, fish are non stressed and eating well - so thats not the question / im not concerned. Just getting everyones view on how much was normal for water evap per day on a summer day.

thanks for all that helped, question answered