Help Salinity problem.

[lacosta28]

I do a water change every 2 weeks and I also have an ATO. I have a 90g tank with 3 fish and various corals. I did a water change around 12 days ago and my salinity was at 1.025. I checked today and it is at 1.020. I have no idea how this happen. The only thing I can think of is I have been working in the tank a lot the last week. So the water that comes out by putting my hand in there must have have dropped the salinity as it was replaced by the ATO.

I planned on doing a water change tomorrow anyway but now I don't know how to do it. I don't want to do a water change and bring the salinity back up and shock everything. Should I skip the water change and top off with salt water until it is back up? The good thing is my fish and corals are all doing great even with the low salinity.

 

[xmenx2dad]

I would think top off with saltwater to slowly raise up your sg

 

[Gomer]

As long as nothing looks stressed, don't make any fast changes. Only very slow ones. Fast = bad 99% of the time. Double check your salinity and make sure your meter matches calibration. Are you using a hygrometer or refract? Makes zero sense to go down in salinity if you haven't done much.

 

[reign]

+1 , I would assume if you using a hydrometer it had a air bubble on it and gave a high (false) reading initially or if using a refract. if it was not rinsed well with ro/distilled water and gave a bad reading...Or you have a small leak somewhere that is not that noticeable and your ato just dropped your salinity (probably not that likely i hope)..I would figure out what is causing the salinity problem first then top off with saltwater if necessary..Btw your fish can take as low as 1.011 w/o issues (if gradual ) it is your coral that is more sensitive to this ...Good Luck !!

 

[Soulsanctu]

you can do a water change. Just make your new water higher than .20 and when it mixes with whats in the tank it will bring it up slightly. And do the same next change bringing it up slightly more. Really don't think water on your hands is going to bring down the salinity,,,,even if we are talking about a 10 gallon....unless you are really, really, messy when your playin in your tank.
Using a hydrometer, I check and recheck, and then check again, just to be sure.

 

[Ntvper]

+1 , I would assume if you using a hydrometer it had a air bubble on it and gave a high (false) reading initially or if using a refract. if it was not rinsed well with ro/distilled water and gave a bad reading...Or you have a small leak somewhere that is not that noticeable and your ato just dropped your salinity (probably not that likely i hope)..I would figure out what is causing the salinity problem first then top off with saltwater if necessary..Btw your fish can take as low as 1.011 w/o issues (if gradual ) it is your coral that is more sensitive to this ...Good Luck !!

+1 with reign/gomer.
check. check. check. and recheck.
I also recommend using a refractometer vs a hydrometer, worth the money, easy to recalibrate, no fear of it giving false readings (and if it does clean, place ro water on it reset/recalibrate).

quick story i used to use hydrometer, thought all was great looking good n such. lost snails like at least half of what i bought. borrowed friends refracto and saw that my hydrometer which stated 1.024 was actually 1.035 now its at 1.024 and havent lost any snails like i use too

 

[Gomer]

Hygros suck. Refracts rule. All there is too it :-D

 

[lacosta28]

I am using a refractometer. I made a new batch of water for the planned water change I was going to do tonight. I tested the water with the refractometer and it seems to be accurate. I checked my tank and sump for leaks and didn't find any. I highly doubt I have taken that much water out by just sticking my hand in there a few times to move some corals. One thing I did notice was a lot of salt build up around the sump. I have always cleaned it off and didn't think much of it. That might be what is causing my drop in salinity. If so I don't know how to stop. I guess I will just have to start testing daily.

 

[paul_111]

Are you skimming very wet? If the skimmer is pulling a lot of water and you replace it with RO/DI top off, your salinity will drop over time.

Paul

 

[lacosta28]

The skimmer is running dry. I am starting to think it is the salt build up I find around the sump everyday.

 

[Ntvper]

its possible on my salt buildup which is around the skimmer and the overflow piping i just rinse back into tank when i see it. i use to clean it up and off away from the tank but was worried the salt creep is coming from my salty water and i would drop my salinity that way too fast so i stopped

 

[Gomer]

Before you do anything: If your tank is visually fine, check against a standard (or let another friend/LFS measure your water salinity with their refract).