Evaporation and water changes

Question
Jennifer,
My tanks are healthy and the creatures are flourishing, coral growth has been
good.  thanks so much.  my question now is with the cold dry weather we are
getting in the Northeast, my tanks are evaporating like crazy;  my 90G is
evaporating at a rate of 2 gallons per day, that is 14 gallons per week.  I am
adding 14 gallons of new fresh water per week, that is more than a 10% water
change.  should I change my water every 2 weeks now? 3 weeks?  or they
have nothing to do with one another and I should still do 1 change per week.   
my RO/DI is working overtime  and I can't keep up with making water.  would
a once a month water change ok?  I have been doing a change once every 2
weeks for the last month.  what are your thoughts.  
Vu

Answer
Hi Vu. I am glad to hear that everything is going good. I too am experiencing a large amount of evaporation and in my 75 gallon I am adding about a gallon of top off water a day. I hope you are doing your top offs as regular as possible and not letting the water level get too far down before you add fresh. Salt does not evaporate as well as the good and bad elements in your water. If you let it get too far down your salinity will raise to a possibly unhealthy level. You need to keep doing your partial water changes as you normally do. The evaporation of water has no effect on the build up of wastes in your tank and those must still be removed according to your regular maintenance schedule. If you are having troubles with your nitrate build up and need to do your partials once a week then keep doing them that often. If you are doing good and everything is thriving and your nitrate is not getting high with you doing them every other week then continue doing that. The frequency of your partials is all going to depend on your tank's specific needs. Every two weeks is working for you now so may be able to cut it back from every week to that. Keep an eye on all your levels and don't worry spring is only 59 days away(I too live in the northeast)!