ATO and Salinity Changes

[saltwatr]

So I just added an ATO to my system and didn’t realize how much of a swing in salinity I would experience from it adding a couple gallons of RODI to the sump.

My salinity went from 1.024 to about 1.021 in a pretty short period of time. What’s the best way to go about getting back to the right salinity without affecting my fish too much? I have two clowns currently and am worried a lot of changes so quickly will harm them.

 

[fish farmer]

It shouldn't swing that much. What are using for an ATO and what size tank? It sounds like something is either sticking on too long or not triggering the ATO to kick on.

 

[Journeyman]

Actually, your salinity should be more stable with the ato. You're just measuring the water to quickly after it's been added to the sump. Once it moves to your display it will be fine.

 

[Journeyman]

Also, are you measuring the salinity in your sump as our immediately after fresh water is being added? That won't accurately reflect the salinity in your display.

 

[Timrpn]

When I check my salinity, I take it from the DT, i don't take it where the ATO is dumping the fresh water.

 

[mike550]

So I just added an ATO to my system and didn’t realize how much of a swing in salinity I would experience from it adding a couple gallons of RODI to the sump.

My salinity went from 1.024 to about 1.021 in a pretty short period of time. What’s the best way to go about getting back to the right salinity without affecting my fish too much? I have two clowns currently and am worried a lot of changes so quickly will harm them.

How did you get so much RODI into your sump? Make sure that your RODI sensor is working right so you don’t accidentally dump more fresh water into your tank.

Guessing your water volume is around 15G. So it will take quite a few water changes to raise it. But easy to do over time. If it’s fish only the salinity should be okay

 

[Journeyman]

Hmmm... Did you fill up the salt water to where you want the top off to go before adding fresh water?

In other words install the ato when your water level is where it is supposed to be, so the ato is off when you first install it. Then it should only at water as you lose it to evaporation and the salinity should be fairly stable.

If so, then something may be stuck or your fresh water is siphoning into the tank when it should be stopped.

 

[slojim]

but if you still want to raise your salinity, I suggest you think about how much water you added, then mix a similar amount of saltwater at your target salinity. Dump it in. Over a few days, the water will evaporate back to its maintained level,the ATO will start pumping again, and your salinity will be right where you want it. (don't raise your sump so high you risk an overflow)

 

[saltwatr]

How did you get so much RODI into your sump? Make sure that your RODI sensor is working right so you don’t accidentally dump more fresh water into your tank.

Guessing your water volume is around 15G. So it will take quite a few water changes to raise it. But easy to do over time. If it’s fish only the salinity should be okay

I think I may have just done a little too much, too fast? Looking back I realized why it went down, but I didn’t expect such a big shift.

Drip acclimated the fish (lost some salt water because I dumped all this out after), then the ATO filled to my “on” line in the sump with RODI. Roughly 1/2-1 gallon salt water out and ~2 gallons RODI in before I realized how much it actually was.

Lesson learned, but I’m just worried about the fish at this point. They seem to be acting normal. Wait for some evap and then add more salt water in instead of straight RODI?

 

[saltwatr]

It shouldn't swing that much. What are using for an ATO and what size tank? It sounds like something is either sticking on too long or not triggering the ATO to kick on.

Measured salinity from the DT only. See post above for what went down, but I didn’t realize it would have that much of an effect on a 75 gallon with 40 gallon sump.

 

[slojim]

FOWLR/fish only? I would let it come back up with evaporation rather than adding oversalty water. You can speed the process up if you like by removing a few gallons of your lower sg water and adding back something well-mixed and just a little more concentrated. In my experience, fish handle drops in salinity within reason pretty well.

 

[saltwatr]

FOWLR/fish only? I would let it come back up with evaporation rather than adding oversalty water. You can speed the process up if you like by removing a few gallons of your lower sg water and adding back something well-mixed and just a little more concentrated. In my experience, fish handle drops in salinity within reason pretty well.

Yeah fish only at this point. I think I’m going to let it evaporate a couple days with the ATO off to gradually get salinity back up. Guess I’ll revisit at that point and add back some salt with the RODI.

 

[mike550]

Measured salinity from the DT only. See post above for what went down, but I didn’t realize it would have that much of an effect on a 75 gallon with 40 gallon sump.

Okay. 2G of RODI on 100G tank (taking out rock and sand) should have only lowered from 1.024 to maybe 1.023-1.0235. Change is even less if you consider 135G.

Maybe your measurement was off?

 

[saltwatr]

Okay. 2G of RODI on 100G tank (taking out rock and sand) should have only lowered from 1.024 to maybe 1.023-1.0235. Change is even less if you consider 135G.

Maybe your measurement was off?

Yeah it seemed off to me as well. I’m no scientist, but calibrate my refractometer at tank temp with RODI and retested multiple times. Thinking about springing for the Hanna salinity tester.

 

[mike550]

Yeah it seemed off to me as well. I’m no scientist, but calibrate my refractometer at tank temp with RODI and retested multiple times. Thinking about springing for the Hanna salinity tester.

Sorry. Just trying to help you figure this out. For what it’s worth I have the Hanna. Very pleased with it.

 

[saltwatr]

Sorry. Just trying to help you figure this out. For what it’s worth I have the Hanna. Very pleased with it.

Thank you for the help! I wasn’t taking a dig at you, just making light of my lack of knowledge here lol. I feel like the Hanna will be a good long term investment for convenience sake. Putting my order in now.

 

[reefshawn]

Really anywhere in that range is generally fine for most aquariums. Over the years the hobby has changed its mind a lot on what the perfect SG is but that range is fine.

Your fish are almost certainly fine. I did lots of terrible things when I first started and fish always seemed fine after swings like that. Corals didn’t like big swings and the delicate ones you want to be careful with.

Your ATO will have a little dial inside of it that lets you adjust how much freshwater gets added whenever it kicks in. If you have a smaller tank, make sure and set an appropriately small pour of water.

When you sample your SG, do not do it immediately after your ATO has kicked in, and do not take a measurement from the same chamber the fresh water was pumped into. Give it some time and space to mix in otherwise you’re going to have a false reading.

Do not take one reading, calibrate your refractometer, then take another. Your ability to compare the two samples will have gone out the window. If you calibrate do so before taking all your samples.

If you need to bring your SG up, I’d leave it for now but on your next water change make the new water a bit saltier than you’re shooting for. Just bring up the SG a little bit over your next two or three water changes.

 

[BeejReef]

If you don't evaporate a ton of water every day, just turning off the ATO is a nice, surefire, simple, and gradual way to bring your salinity back up. You have your fill-to line. Turn off the ato and make up for your evaporation will saltwater by hand for a day or three until your salinity is back in line. If you fear that approach may be too sudden, then make up for your evaporation with half-strength saltwater.

 

[sarcophytonIndy]

I think I may have just done a little too much, too fast? Looking back I realized why it went down, but I didn’t expect such a big shift.

Drip acclimated the fish (lost some salt water because I dumped all this out after), then the ATO filled to my “on” line in the sump with RODI. Roughly 1/2-1 gallon salt water out and ~2 gallons RODI in before I realized how much it actually was.

Lesson learned, but I’m just worried about the fish at this point. They seem to be acting normal. Wait for some evap and then add more salt water in instead of straight RODI?

Your fish should be fine, just don't do anything drastic to raise the salinity like dumping in a bunch of salt. I would just let evaporation take its course and you will gradually be back up to normal in a few days.