Evaporation Rate for a 75 Gallon Reef with MH lighting and no glass top

[diane4]

Help, I am beginning to feel like I live in a fish tank or I am always lugging water.
I am insane, yes. I have 6 fresh water tanks and 2 saltwater tanks. Total water volume in tanks in my house is about 700 gallons.
Anyhow, I have a 75 gallon reef tank 48" long and I think 20" high. I have the Coralife Auqalife pro MH lighting with the 2 actenics and 2 lunar lights. I have removed the glass top and I am running an air conditioner and a cieling fan to keep it cool, around 80F. The issue I am having is that the tank goes through about 2 or 3 gallons of evaporation every day. I constantly have a large trashcan filled with R/O pre-buffered water in my kitchen that we walks sideways around because it takes up so much room in my tiny kitchen to begin with.
I have the 48" MH lighting unit on the standard legs that come with the lighting system. I have already removed the glass top for ventalation and cooling, but that only further increased the evaporation rate. My 90 gallon fish only tank that has a glass top only uses about a gallon every day or other day, compared to the reefs 2-3 every day. 3 times the rate of evaporation in the reef tank.
And to add insult to injury of my insanity, I will be converting my 120 gallon fresh water tank to a saltwater fish only tank.
I am overwhelmed with water evaporation and storage of prepared R/O buffered water.
1) I was wondering, how can I reduce the evaporation time and yet keep the tank cool?
2) For you BIG tank folks, where do you prepare and store your R/O water for changes and top offs?
3) And lastly, I have read on this forum that it can help to raise the MH lighting unit a bit by hanging them from the cieling. How high from the top of the tank do you recommend and how do you hang them? Does anyone have pics of how this looks?
I appreciate your advise, in advance.
I am so excited, I will be getting a guineafowl puffer as soona s I convert the 120 fresh water tank.
Thanks a bunch.
Diane

 

[lubeck]

If you are blowing air across the top of the water to help cool, which is what your supposed to do, you will have that evaporation loss rate. Between your lights and normal air temp you will have about a gallon or 2 but... if you are actually blowing air across the top... whcih is very effective in cooling the water down... you will have a little less than DOUBLE the evaporation. IMO
As far as the lights go... i have my 650watt of Mh lighting about 7inches, which is a little too close, they recommend 8-14 inches above the water surface.
I don't know if you have seen the post SQUIDD I AM ALMOST READY TO MOVE TO THE BASEMENT. If you have a basement that would be your best bet. I moved all my filtration 75gal sump/fuge for my 110gal reef to the basement which is almost 10degrees cooler already. This would help you out. I go through almost 3-4 gallons a day but will be hooking up my auto top off so I won't have to keep topping off with fresh ro/di water.
I use a 55gal. rubbermaid stricklty for fresh salt water batches and mix it with a 9.5mag drive and use a 30 gal rubbermaid STRICTLY FOR FRESH RO/DI TOP OFFS.

 

[ppp]

Are you running a sump under the 75? When I changed from a wet/dry filter to a sump, my evaporation rate went from 1/2 g. per day to 2 gal. I partially covered the sump with glass and it cut the evaporation in half.

 

[diane4]

Yes, I have a sump and I don't keep it covered. Interesting concept, I will cover the sump, that might help.
It's an easy 2-3 gallons a day for top offs.
I think I would like to raise the MH lighting system higher over the tank. I think the lights are to strong or too much for the animals. The anemones have climbed under rock to hang out, they dont' like the MH. They didn't hide when I had PC lighting. I have all soft animals, no hard corals. I sometimes regret getting the MH lighting unit that cost me a bund, like almost 700 bucks. I think I did better when I had the 50 gallon reef tank with strong PC lighting.
Do you know how to properly hang the 48" lighting system above the tank? Advise or pics would help. Thanks. The lights are heavy and I want to make sure they are secure.