Evaporation Water Change?

[dale serbousek]

I have a fan blowing across the top of my water to keep it cool. I maintain an even 75-76 degrees;however, I loose about 1 gallon of water a day to evaporation. As I replace the water with dechlorinated fresh water, can I consider this the same as a water change? Or, do the nitrates remain in the water during evaporation? I am currently doing a 2 gallon water change every 2 weeks in my 37 gallon tank.
Thanks

 

[ken s]

no this is not a water change. the water that evaporates is pure fresh water, the nitrates and other nasties stay in the water, you need to actually dip out water to remove nitrates. then replace it with ro/di water.

 

[q]

No it is not. If anything the levels increase as the concentration would become higher. The only way nutrients are removed from the system is by taking water out and replacing it with clean freshly mixed new salt water.
Your temp seams a bit low for me. I run 80 plus or minus 2 degrees from temp swings. You also might want to consider using a smaller fan as heat is not an issue. It will reduce you evaporation.

 

[dale serbousek]

Ok, I understand about the water change issue...I kinda figuerd that. As far as the temp issue goes...I was getting temps into the 85-88 degree range w/o the fan. I do not have an air conditioner because I live in a relatively cool climate near Canada. I have 165 watts of PC under an Eclipse hood...so that tight hood acts like an oven. I cut a hole in the side and mounted the fan on the side. It works great. I also have read that 75 degrees is the optimum range. I have read several current books saying that overall water condition will be better around 75. They say 82+ is ok, especially for breeding, but that higher temps like this will only raise the metabolism of inhabitants which in turn shortens their life in the long run.
Any thoughts?

 

[frankl15207]

I think this was a topic switch but...
Generally the temperature is recommended at between 72 and 78 degrees, so 75 is right in there. I keep mine at around 78 more because of the surrounding environment (ambient temperature is high because someone in house has circulation problems and is always cold). 82 is on the high end and will stress some of the inhabitants. Above 82 for any duration will cause problems.
I replace about a gallon a day on a 75. If you are doing that on a 37, it's a 2% loss/day. You may want to try to split your addition of replacement water up to twice a day to avoid a drastic change in the salinity. Replacement water brings the salinity down to it's previous level, and 2% can be significant enough to cause problems for some sensitive creatures if it's all done at one time.

 

[q]

The most diverse coral reefs are found in a band running from Palau in the Western Caroline Islands through Indonesia (Veron 1986). In this area the atoll water temperature averages around 84 degrees Fahrenheit (28 degrees Celsius) — and probably never gets as low as 80 degrees (around 27 degrees Celsius) — and the salinity on the reef faces generally is in excess of 35 parts per thousands (ppt) (Sverdrup et al. 1942, Brandon 1973). Most of our corals and the associated fauna, including fish, will live best at these conditions (Weber and White 1976).
I coppied this from an article Dr. Ron did on temp and salinity.
The full article is <a href="http://www.animalnetwork.com/fish2/aqfm/1997/nov/features/1/default.asp" target="_blank">HERE</a>