So much evaporation I thought there was a leak????

[Vinman75]

Question that may be hard to answer but I wanted to get peoples thoughts. I have a 55 gallon FOWLR tank and for the last 2 years or so I had been using a 2 bulb T5HO Current llight. 2 54watt bulbs. a White and a blue actinic. I had the light on for 6-7 hours a day and then would turn it off. It helped minimize some of the algae growth and all. During this time I would have to add waterr/top off every 2-3 days. Probably a little less in the summer when the house was not as dry.
A couple of weeks ago I bought a great Aquaticlife light. This one is 4 54 watt bulbs that are on a time. The bright lights are on for 9 hours or so during the day and then the bright light dims for an hour in the morning and evening and then the lunar lights are on at night.
Over the last week or so, as it has gotten a bit dryer I have noticed a huge change in the amount of evaporation. In that if I dont put water in every day, I have trouble in that the water level drops in the tank and the sump so that it starts to sputter. This has caused some problems with the tank in that I have to turn off the return pump and try to balance the levels of water in the sump and tank. (not sure if any of this makes sense other, than the enormous increase in the evaporation of water in the tank)
It reached a point where the increase in how much water that I was having to add compared to previously almost made me consider that I had a leak of some sort. after leaving the pumps off for a bit there is no leak.

I guess my question is: From my change in lights. doubling the size and having a nonstop light, (2X's the daytime output, dimmers and Lunar

 

[Bobbofin]

I have forced hot air heat that I just turned on last week. I also have a 4x36w Aqualife T5 fixture over the tank. I go through 5 gallons of water a week during the dry winter heating season and maybe 2 gallons in spring, summer and fall. The dry winter air absorbs moisture a lot.

 

[Steviereefs]

+1 , you doubled if not more your output , the surface temperature increases and causes more evaporation. On the 75 gallon tank I had, I was topping off a gallon per day.
1st step: check salinity
2nd step: likely since you've topped off regularly your salinity is not too out of check other than just what has evaporated , salinity especially in a fowlr can easily be adjusted down quickly to the proper level without a negative impact on the inhabitants.
3rd step: top off. Add the fresh water to the sump directly if possible, if not then to the overflow till your pump stops bubbling.
After it finally stops bubbling you need to check you salinity.
4th step: now is the time you say you salinity is either to high or at the original point , either at this point simply add more fresh water to dial in your salinity, Or you will already be where you want to be and don't need further adjustment.

 

[Roccus]

My 75 ( with open sump) with screen top and 2 Current orbit pro LED's uses about 5 gallons a week... close to 7 gallons during heating season....my 65 closed top( glass) with a single LED strip uses about 2 gallons a week.. my 20 screen top with LRD's uses about a pint a day...I top off daily... my 29 bio cube with compact fluorescents that is totally enclosed uses less than a quart a week... My recommendation is to set up an ATO if topping off is an issue...

 

[this is me]

How much water are you actually losing? Is the tank open top? is there a fan blowing across the water when the temperature gets too high? Any surface water turbulence? Any of these will factor in your evaporation.
I'm losing about 1-1.5 gallons a day on my 200gallon systems open top.

 

[JohnK]

What type of overflow are you running? Is there any chance that it has become obstructed or otherwise slowed down?

A seasonal increase in evaporation isn't surprising, but it sounds like you are seeing more of a change than would be expected so I'm looking for any other contributing factors.