Going crazy trying to raise salinity with AWC and DOS

[Nightwatch]

The background:

- My salinity in my DT won't go above 1.024 with current AWC setup. Sounds stupid, but read on.
- AWC is setup using a DOS, pulling from my mixing station in the basement, and dumping old water directly down the drain
- I have an ATO setup, which automatically fills from a basement RO reservoir (all tested and good to go), which tops off the sump. It does seem to come on fairly regularly due to me being at altitude (7,000 feet) in Colorado (dry). But we are talking maybe a few times an hour for 10-15 seconds.
D)I am using a Milwaukee MA887 to test salinity, and I am calibrating, cleaning, and testing as per the instructions (using included distilled/validation solutions)
E) I have also tested with a refractometer - also calibrated using refractometer solution at 35PPt etc.
F) tank is a Reefer 250, so about 60 total gallons ( a bit less as there is live rock)
D) Nothing in the tank other than cycled Caribsea rock and one small zoathid.

Step1) Tested DT water yesterday. 1.024 specific gravity.
Step 2) Had pre-mixed Salt in mixing bin - mixed for 16 hours or so, and its the tropic reef marin pro. Measured using milwaukee, and it show 1.029. Intentionally high as I wanted to raise the salinity in the DT, and its only about 17.5 gallons
Step 3) Last evening I turned on the Neptune DOS AWC setup and let it run over night
Step 4) This morning, verified all 17.5 gallons had been drawn from the mixing bin, indicating it had obviously gone to my tank
Step 5) Tank levels (sump etc) look exactly as they should - so water going out equalled water going in...I think
Step 6) Tested tank - 1.024. No increase at all. Tested 3 times, 3 separate calibrations. Tested with Refractometer too. 1.024

How is this possible? Now one thing I did notice is I tested the Milwaukee with the included validation solution, and it came out to 1.026, rather than 1.025 like it's supposed to. Cleaned everything several times using soft cloth and RO water - same thing. So the Milwaukee is a little off. But the Refractometer is validating the same readings.

How is it possible I changed out 17.5 gallons of a 60 gallon tank going from 1.024 to 1.029 and Im not seing the salinity of the overall tank rise to 1.025 or so? I should note I tried this two days ago using 1.026 water in the basement but again, no change. It's maddening?

Last note - yes I know I can do a manual change with higher salinity water which will obviously work. But the point here is somehow Im concerned my AWC system is not doing what it is intended to do. Am I somehow having a back syphon pulling from the tank, which is being compensated for by the ATO? My "old water" drain line for the DOS is in the drain area, and my new water from the mixing bin adds to the return area.

Uggg

 

[takitaj]

Are you turning off the ATO during the water exchanges?

 

[Nightwatch]

Are you turning off the ATO during the water exchanges?

No...I assumed because the AWC is a constant (taking out the same amount that is going in) and its relatively slow, the ATO didn't matter because it was just keeping up with evaporation. Am I thinking about that wrong?

 

[rtparty]

Couple things...with what you have in the tank there is zero reason for AWC right now. It's a waste of water and salt.

Second, just fill a cup with some salt and place it in the sump. It will very slowly dissolve and raise salinity.

Done. You really are making this much harder than it needs to be.

 

[Nightwatch]

Couple things...with what you have in the tank there is zero reason for AWC right now. It's a waste of water and salt.

Second, just fill a cup with some salt and place it in the sump. It will very slowly dissolve and raise salinity.

Done. You really are making this much harder than it needs to be.

OK - I was just trying to gently raise the salinity while also working out the bugs with the AWC etc. Probably overkill yes, but I wanted to have everything dialed in for adding more corals etc.

Question about adding salt to the sump - I had read that adding salt directly was a really bad idea as it could burn livestock (the zoa?) without premixing. Are you sure its ok to add salt directly? I definitely wouldn't do that with fish in the tank, but maybe it's ok with the tank only have a zoa in it?

 

[Jon's Reef]

It will probably take between 1/4 and 1/2 cup of salt to raise it from 1.024 to 1.025.

I would just slowly pour it in the sump near the return pump. If you want to be more cautious, that is 4-8 tablespoons. Just put 1 tablespoon per hour until you get the right number.

 

[flagg37]

I would have your apex turn off the ATO while the WC is happening. If you are having the 17.5 gallons taken out and then put back in then there would be a time that the water level in your sump would be low and the ATO would be running. If you’re using both heads on the DOS to simultaneously take water out and add it then there shouldn’t be that problem.

Aside from that, 1.024 isn’t really that bad. Your fish probably enjoy it. I know people that run theirs at 1.028 and it’s mostly just to have increased elements. 1.026 isn’t a hard and fast number that needs to be kept. Just keep it consistent.

 

[fachatga]

Or just use some saltwater in the auto top off for a little while. Will raise it slowly which is better than doing it all at once with a water change

 

[2una]

Leave the salt in the cup & put it in the sump is what rtparty was trying to say i think, i do it the same way & it works fine, just slowly dissolves, I also do mag the same way.
This is a good calculator for it here - https://www.hamzasreef.com/Contents/Calculators/DirectSaltCalculator.php

 

[Nightwatch]

Leave the salt in the cup & put it in the sump is what rtparty was trying to say i think, i do it the same way & it works fine, just slowly dissolves, I also do mag the same way.
This is a good calculator for it here - https://www.hamzasreef.com/Contents/Calculators/DirectSaltCalculator.php

Genius! On it. Thank you all

 

[DiamondHands]

Genius! On it. Thank you all

2unas method is interesting. I tend to just dump a cup of salt mix into a filter sock.

With regards to the AWC.

1. Check your DOS calibration.
2. There's a chance your ATO is super sensitive and has a minimum run time. I might try limiting your ATO to running just during a 2 hour period per day. I suspect it would dose more in that period, and less frequently. Less on/off cycles would result in less "excess" if your ATO is super sensitive. When I didn't have an ATO, I just dumped in top off water manually once every day or two, so I really don't think it would hurt to give it a shot.

I have a DOS and Osmolator, and doing AWC is something I've been doing without the result you are facing. I go through about 3 gallons of RODI water per day on my display tank.