Salt in ATO to compensate for waste water

[Gogi]

I'm running my system using the Triton method and I'm using the GHL KH Director. The lack of water changes combined with constant removal of water (KH Director waste water and skimmate) is resulting in slow but steady salinity drop. Nothing shocking there.

I was just wondering how others in similar situation deal with this? I was thinking of finding a good level of salinity for my top of water to offset the dilution. Anyone done this?

 

[JasonK84]

I’ll follow along here. I run a 120 fish only tank and don’t do any water changes. Nitrate remains “0” with the amount of media I run and phosphate is brought down using lanthanum chloride and or GFO in a reactor.

I was wondering this a while back. My SG is currently 1.023 and that’s fine for a fish only system but I think my skimmer may perform even better at a higher SG and producing a thicker drier skim and not need to run it as wet as I do currently.

 

[CNDReef]

I was contemplating doing something like this with a doser. I was going to replace exactly what the khd was removing but have since sold the khd.

 

[mcdrichj]

If you put salt in your ATO then your salinity would be all over the place because your evaporation rate changes with the room conditions which would change how much salt you need in the ATO water. You would essentially have to dose in what the GHL takes out. I would take a graduated cylinder and see how much it uses in an hour and a day. Then try to make up the difference with a separate doser of regular saltwater (with a lid to prevent evaporation) and keep RODI in the ATO and let that do its thing.

 

[Gogi]

I don't think I can find the space for another large dosing container haha.

 

[mcdrichj]

I don't think I can find the space for another large dosing container haha.

After finding the proper dose of the triton additives your alk should be pretty stable. At that point its not necessary to test so frequently. Can you reduce the test frequency of the GHL? (I dont have one but I imagine you can change this). I would reduce the testing to once a day or every other day them manually add the proper amount of saltwater weekly. I would get a graduated cylinder and see how much water is used in 1 test then figure out your frequency from there.

 

[phatduckk]

when my salinity gets low I just add salt water to the DT; so essentially it’ll take more evaporation before the ATO even turns on. Sometimes I’ll even turn the ATO off and “wait” till my salinity is where I want it to be then I top off with salt water and turn the ATO back one.

 

[Reefs and Geeks]

Simplest way would be to make occasional additions of saltwater to offset the water pulled for testing. The most consistent way (though I doubt it matters much to be this precise) would be to set up a doser to dose saltwater at the same time and rate as it's removed for testing. With anything but a very small system I'd go with the former as it's simple and would be a good time to check salinity anyways. Maybe do once every week or few weeks depending on the size of your system.

 

[Randy Holmes-Farley]

Are you sure salinity is declining? Many alk and calcium addition methods boost salinity.

 

[CNDReef]

The kh director uses minimum 80ml per test. Depending on how many test per day and the size of his system he can drive his salinity down pretty quickly. I had the same problem on my other tank and sold the kh director because of it. Solid alk but salinity would swing a lot.

 

[Gogi]

Yeah, sample size is pretty large. In fact the amount of used water is actually greater than the sample size because KHD flushes the test cell first.

For now I used a calculator to figure out how much salt to use to fix the current salinity offset and dissolved that in my ATO in order to bring it back up slowly over the course of a few days.

I'll need to figure out something more permanent. If I can make some space for a salt water reservoir, I'll start automatically dosing it. Love my KHD too much to let this get me down

 

[Gogi]

Are you sure salinity is declining? Many alk and calcium addition methods boost salinity.

Yes, that would be great. But at 4x80ml+ samples per day it's unfortunately more than the additives add. As @mcdrichj said, I'll eventually reduce to 1 or 2 samples per day.

 

[Randy Holmes-Farley]

Yes, that would be great. But at 4x80ml+ samples per day it's unfortunately more than the additives add. As @mcdrichj said, I'll eventually reduce to 1 or 2 samples per day.

If you know that to be true, it is fine to put a little salt mix in an ATO. In a bigger tank with substantial demand. using a two part, the salinity increase can be a bigger than that dilution will account for.

At 1.1 dKH added per day, a two part will boost salinity by roughly 32 percent over the course of a year. In a 100 gallon tank, that requires swapping out 32 gallons per year or 331 mL per day.