Having trouble keeping my salinity level consistent

nport19 · Feb 10, 2015

Hi i have a 20 gallon reef setup with a heater that is set to 75 degrees and led lights that's are fairly strong. I have noticed that my salt levels on the tank seem to go all over the charts and never seem to stay in the idle zone for long. Is there a way that I could slice this problem? Also if anyone could give me some advise as to what salt levels work for them that would be great.

srva80xx · Feb 10, 2015

Might want to warm the tank up a little.. 77-80

I would recommend salinity of 1.024-1.026, you could go lower if you don't have any corals.

The only reason I can think of that would cause your salinity to fluctuate would be evaporation. Look into an auto top off.. you can get a nano one for around 100 bucks

Randy Holmes-Farley · Feb 10, 2015

Is the water level being allowed to change due to evaporation and fresh water replacement? That is what would cause salinity changes.

In general, there is no reason to not aim for natural ocean salinity levels, around 35 ppt, or a specific gravity of around 1.0264.

srva80xx · Feb 10, 2015

and you are topping off with RO water correct? Not salt.. could you tell us what the levels are changing to?

nport19 · Feb 10, 2015

Thanks for the advise. My salinity level I have been going for is 1.23-1.24. I think I going to try to keep it in this range. I will also try to move up the temp in my tank a little as well.

nport19 · Feb 10, 2015

Evaporation does I think play a big role as to why the salinity keeps changing and when I do top offs I usually put just freshwater in and if it's not at the correct salinity level then I put salt in it.

nport19 · Feb 10, 2015

The levels that it usually changes to when I do a freshwater top off is in the low range. I can't really give numbers because I'm not by my tank at the moment. For the salt top off it usually goes up to around 1.026 or 1.027 which I thought for a while was to high.

Randy Holmes-Farley · Feb 10, 2015

Ignoring measurement differences, which could be error, how much is the water level on the glass actually changing when you top off?

If the tank is 20" tall and you drop by 1/4 inch, the salinity rises by about 1.25%. So 35 ppt becomes 35.4 ppt, or sg = 1.026 becomes 1.0263.

So that seems like a reason target level change to not exceed.