Salinity dropping

[Dan7575]

Hi all,

I make up my salt mix to around 1.024/1.025 and hold my hand up and admit I don’t really check between water changes but I am on a drive now to maintain stability in the tank and have just tested and it is down to 1.020. I have rodi water in the ATO and as it is the middle of summer here in Sydney I suppose the evaporation is high so the rodi water is dropping the value. How would I keep the salinity stable? Should I be putting in a weak mix of saltwater into the ATO? If so how would I calculate what that should be?

Dan

 

[Frey]

Skimmer may be removing some of your salt also. You could add some to your ato but if you are evaporating very quickly you may add salt back in faster than you may want. I do this on occasion, i have had my skimmer go nuts and dump water on the floor so i have mixed a bit into the ato and kept doing it slowly until i got salinaty back to where it was. Just do it in small increments

 

[reef lover]

Double check your test before doing anything drastic...

 

[lapin]

Since I know my skimmer takes out about 5 gallons a week I mix my water change water a bit higher than 1.025 to keep my tank from dropping over time.
Evaporation will not remove salt. It will remove water making your tank higher in salinity if you do not replace the water.

 

[homer1475]

When I run into this issue about twice a year, I simply mix up my weekly WC water to higher salinity. Like 1.028 or 1.029. 10G wc on my 85G system usually will raise my salinity by 1 or 2 points. Then I just continue next week with the higher salinity WC until I reach where I want it to be.

Topping off with salt is also an idea, but you have to test daily and catch when it reaches the right salinity, or you can easily overshoot and your dealing with another problem.

 

[C_mo97]

Is the water you are putting in at the same temperature when you do water changes?

 

[ReefGrammie]

As others have said, I generally mix my water change at a slightly higher salinity than my tank. I have a sump/refugium and tend to get a lot of salt creep, which I periodically scrape off the walls back into the sump. The water should also be at the same temperature as the tank, so I have a heater in my water change bucket. I also run a power head in the bucket to ensure the salt is completely mixed/dissolved before the water change. I would be afraid to put saltwater in my ATO. I don't know for sure, but it seems that might create problems down the road. Good luck!

 

[Dan7575]

Is the water you are putting in at the same temperature when you do water changes?

At the moment yes as it is just the ambient temp which is a bit high at 27 - 29 deg because it is so bloody hot, no need for heaters at all.

 

[Dan7575]

So should I expect there to be swings in salinity then if the idea is to mix the WC water higher so that it compensates, if so what is a safe swing?

 

[BeejReef]

How long did it take to drop from 1.025 to 1.020?

If over many weeks or months, you might look into marginal stuff like the skimmer cup or salt creep. If it's happening over days or a week or two, you must be missing something more substantive.

How long in advance of WC to you mix your salt? My mix bucket tends to test 1.025 when I put in the last scoop of salt, but will often seemingly drop to 1.023 2 hours later.

Also, last week my salinity measured low. I found that an algae covered strainer inside my overflow had raised the DT water level by a centimeter and the ATO had filled in a corresponding amount into the sump.

 

[Quietman]

When I clean out skimmer cup and a week of testing I usually pour in saltwater from storage to compensate. There should be no need to add SW to ATO. Bring salinity back up, keep an eye what you're removing and add back in. Plus check salinity a couple times a week in high evaporation conditions.