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.

[wbdevers]

The amount of water that you would remove on your hands and arms is negligible to say the least, especially dropping .005 in SG. I would guess you've got salt creep somewhere and as your water evaporates, your ATO just adds the RO/DI water back. Normally the salt would still be in the system, but creep removes the salt. Check around your entire tank for salt "blossoms". Worst case you could have a small leak, which now that I think about it may be most likely your problem.

HTH and good luck.

[briankmarsh1980]

What are you using to check salinity? A hydrometer is not very accurate and temp will effect readings. If you are really that low top off with salt water until you are back up to .026. You would have to be putting your hanfs in the tank a lot to lower it by that much

[lacosta28]

I am using a refractometer to check. I checked around the tank and I don't see any water leaks I do see a lot of dry salt build up around the sump however. Could this be the culprit?

[manvsfish]

Agree with 1980! Curious do use refrac or hydro

[wbdevers]

Yes, I'm willing to bet it is. Get your salinity corrected and then keep an eye on the spot that you found the salt. Keep putting it back into your sump and see if you SG doesn't stay correct. You have to remember that every little bubble that pops will drop salt and once a "seed" crystal is started it attracts more salt. Just one of those things. I wipe areas around my sump a couple of times a week.

[Lynnmw1208]

I had a problem with slight splashing in the sump, more like bubbles I would say that was creating salt creep lowering my salinity. I had to buy acrylic sheets and cut them to fit on top of my sump. it helped a lot! now I can just dunk the sheets in the water to replenish that salt.

[clownfreak]

It may also be leaving in your skimate. If you skim very wet and need to empty the cup every day or two, but other than that the salt creep in the sump is the most likely culprit imo

[disc1]

Don't put the salt creep back in the tank.

[briankmarsh1980]

Don't put the salt creep back in the tank.
Why not?

[Jim.mer]

Thats the strangest thing, you have a 90 gl tank,the amount of water being displaced to cause this would be quite a bit, chech your ATO, and maybe your Refractometer

[lacosta28]

I did think it was very odd and thought my refractometer was off. I tested it on water I just made and it was on. I plan on taking my water into my LFS so they can test it. I just want to make sure before I make a decision to do anything.