Calculating the amount of water to remove to lower salinity.

[Tuffloud1]

I currently use the 2 part BRS/Tropic Marine hybrid balling method.

Since I already have auto water change setup, I’d like to automate a specific amount of tank water to be removed per day in order to keep salinity at 1.025-1.026. It tends to creep up to 1.027 if I don’t remove tank water regularly.

Curious if there is an equation or calculator that would tell me how many gallons per day to remove.

Currently dosing 330ml of soda ash per day along with 330ml calcium chloride and 660ml Tropic Marine part C. System is 300 gallon total water volume. Thanks for the help.

 

[Randy Holmes-Farley]

If you are at sg = 1.027 and want to get to sg = 1.025, you would replace 1-25/27 times the total water volume, or 1-0.926 = 0.074 times the total water volume.

 

[Garf]

I currently use the 2 part BRS/Tropic Marine hybrid balling method.

Since I already have auto water change setup, I’d like to automate a specific amount of tank water to be removed per day in order to keep salinity at 1.025-1.026. It tends to creep up to 1.027 if I don’t remove tank water regularly.

Curious if there is an equation or calculator that would tell me how many gallons per day to remove.

Currently dosing 330ml of soda ash per day along with 330ml calcium chloride and 660ml Tropic Marine part C. System is 300 gallon total water volume. Thanks for the help.

There's probably a reason as to why I'm wrong but, my bicarb has an s.g. of about 1.040 and the calcium chloride appears to be 1.045 or so with Randy's 2 part recipe #2. These were extremely rough dilutions, more out of curiosity than anything else, made on a refractometer. I think that would turn your 330 MLS of each into about 1 litre each day for removal. I expect @Randy Holmes-Farley will put me right.

 

[Randy Holmes-Farley]

This is from the Recipe article;

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 sulfate solution, 2440 mL/year), the following residue (Table 3) would remain after calcification and adjustment for salinity (there is roughly a 29% rise in salinity over a year using this addition rate without water changes):

Thus, at an alk addition rate of 1.1 dKH per day, you would remove 29% of the water volume per year, or 0.079% per day.

The effect is linear with dose, so just scale it to your alk dosed per day.

 

[Garf]

So 1 litre a day looks pretty close, soo that's just over 3 times (3.2) the volume of Alk by bicarb (80grms/litre). That's handy;

Edit, appears the OPs consumption is 0.8ish DKH, not 1.1, so this figure would be amended to 780mls a day, I think, lol. So that's 2.4 times the Alk dosed, which is still handy.