Two part salinity increase. Is there a calculation to predict this based on daily two part use?

[Velcro]

@Randy Holmes-Farley

I was wondering if you (or anyone else) has come across a calculator to determine how much salinity is being added over time with two part use. I’m using DIY part 1 and part 2 plus balling C and I’d like to determine as part of my weekly maintenance how much saltwater I could remove and replace with water to stay ahead of the salinity increase. I’m assuming if I know how much of each component I’m using then it should be possible to come up with an approximate amount in this situation. Any thoughts?

 

[A_Blind_Reefer]

That would be nice. I just set up my awc to pull more out than it put in. Trial and error really. I’ve been off two part for awhile but I think I was taking out 200, no more than 250 ml more daily than I was putting in (on a 200 gallon system). It was pretty close to the amount of alkalinity I was dosing daily. Just as a completely random reference with absolutely zero science or data behind it.

 

[Randy Holmes-Farley Verified Community Expert]

I've not seen anyone build a calculator, but it's not hard to model it. I've posted the calculations before. The answer is fairly similar regardless of the two part used:

Residue Remaining from Recipe #1 when using Recipe #1, Part 3A

After one year of adding 8 ppm of calcium and the accompanying 0.4 meq/L (1.1 dKH) of alkalinity per day (41 mL of both parts per day or 4 gallons of both parts per year in a 50-gallon aquarium, including the effect of the magnesium part #3A, 2440 mL/year), the following residue (Table 2) would remain after calcification and adjustment for salinity (there is roughly a 32% rise in salinity over a year using this addition rate without water changes).

 

[Velcro]

Crap I forgot about water changes. I guess it’s be easy enough to work in a 10% weekly water change to the math