HELP! Unstable Salinity

FLReefGirl · #1 04/04/2007, 07:39 PM

For the last 4 months I've kept glass tops on my tank. I only had to top off 2 maybe 3 times a week at most.

Well, last week I decided to remove the glass tops to allow for better/more light. Now I have to top off 1 gal every day. No big deal but... We usually top off w/ fresh RO right? I've been doing this and my SG went from 1.025 to 1.021 over a few days. I nearly lost my open brain and now my sun coral looks like it's starting to recede.
What's going on?

Please help

Blown 346 · #2 04/04/2007, 07:51 PM

When water evaporates the salt doesnt, the salt level would actually go up. Your skimmer on the hother hand does skim salt water, that might be the problem. Evertime you empty your collection cup and add water, you might be forgetting about the salt water in the cup you discard.

I have done this to many times.

FLReefGirl · #3 04/04/2007, 08:01 PM

But why all of a sudden? The tanks been running for 4 months and I've had the PS for 3 months. This only started when I removed the glass tops.

Blown 346 · #4 04/04/2007, 08:03 PM

Salt will not evaporate. Im not sure unless your fish are splashing out water unpurpose to get some laughs.
Seriously, I couldnt tell you the reason, it doesnt make sense to me.

FLReefGirl · #5 04/04/2007, 08:10 PM

Blown 346 - Thanks.

Anyone else?

rocketman2005 · #6 04/04/2007, 08:44 PM

pretty good question, the only thing i could think of would be fish splashing or some other way for water to leak out of the tank, you've really got me stumped!

jmait769 · #7 04/04/2007, 08:44 PM

Like Blown 346 said the SG should go up as the water evaps without adding any topoff. What are you using to measure SG? Maybe it needs calibrated.

Jay

shag26272 · #8 04/04/2007, 08:47 PM

what are you using to measure the salinity

Amador · #9 04/04/2007, 08:53 PM

I have had this happen before and in my case, I had a "fill to here" line on my sump that I topped off to, but that drove my salinity down because:

1) the skimmer is skimming out salt water (especially if you are skimming wet)
2) if you put your hand (or arm) in the tank and take it out, you've just removed water from the system.

Both of these have the same net effect: removing water from the system. So while it would seem like you would have to top off 2 gallons (for example) without checking the SG (going by the fill line alone), in actuality you only need 1 gallon, because the skimmer took some out and you took some out with your hand (or a fish splashing).

What I do now is to check the SG before I top off, then decide how much to add based on how high my SG is.

Hope that makes sense!

FLReefGirl · #10 04/04/2007, 09:11 PM

Thanks everyone.

I've been using a refractometer to test SG. I even rechecked it just to make sure it was working.

It just seems so weird that since I removed the glass top my SG goes down when I top off. I know that normally only water evaps and salt remains but in this case the salt is going somewhere. My PS isn't skimming any more than usual (1 cup / day).
I guess I'm going to have to watch it and top off w/ SW if this continues. That's what I did today.

Henry Bowman · #11 04/04/2007, 09:24 PM

Like others have stated. Your PS is taking out a cup of salt water a day, thats close to 1/2gl of saltwater a week. i dont think taking the top off is related to losing salt or changing salinity.

I'd watch the exact quantity of liquid you take out of your PS and add it back in mixed SW at 1.025 once or twice a week. Then add the RO/DI to compensate for evap.

HTH

FLReefGirl · #12 04/04/2007, 10:17 PM

Thanks!