Continuous Water Change - New Salt Water Storage

[Spectre66]

so I am trying to get to the point that I am continuously changing 1% water daily but am finding my new SW mix drops in Alk within a week or two. Using Red Sea Salt the mix went from 8dkh to about 6.5dkh in 3 weeks. There is some precip in the 55g drum I mixed it in. I am storing the water at room temp or approx 73 deg F.

So is this something that is expected? Saw the Red Sea batch results put Mg at 1300.

Should I try checking Mg levels and bringing it up higher to try to hold off the precip?
For those of you implimenting a CWC system, how often do you mix a new batch?

 

[Randy Holmes-Farley]

Do you stir it? Local heating on the pump might accelerate precipitation.

A little vinegar added to it might also prevent precipitation, if that''s a substantial goal.

I made my IO once a month or so.

 

[Spectre66]

Do you stir it? Local heating on the pump might accelerate precipitation.

A little vinegar added to it might also prevent precipitation, if that''s a substantial goal.

I made my IO once a month or so.

I was stirring it with an MP10 for at least two of the weeks. I did have a hydor korelia in the water but I think it was unplugged most of the time. It might have been on for a week.

How much vinegar should I try adding? I am mixing ~50g at a time.

 

[Randy Holmes-Farley]

I've not tried it before, but 45 mL of vinegar per 50 gallons (0.5 meq/L; 1.4 dKH equivalent of acid) will have quite a substantial pH lowering effect (down into the upper 6's or low 7's), reducing the precipitation. Maybe start with 10 mL and see what happens. Note the alk may test lower initially, but none is lost. Once the vinegar is metabolized by bacteria (in the reservoir or in the tank), you get it all back.

People have done this with muriatic acid, and gotten less precipitation, but the alk is gone for good that way.

 

[Spectre66]

So in your first reply you made the comment if thats a substantial goal... im guessing that lowered alk isnt something that you are concerned with and you just make up for the reduction with limewater added to the tank, correct?

 

[Randy Holmes-Farley]

So in your first reply you made the comment if thats a substantial goal... im guessing that lowered alk isnt something that you are concerned with and you just make up for the reduction with limewater added to the tank, correct?

Yes. Depending on how you dose and your tolerance for alk changes, the effect may be considered small.

Changing 1% daily, say the water is 12 dKH and the tank is 8 dKH.

That 1% adds 0.04 dKH per day.

When the reservoir has dropped to 7 dKH, we have it depleting the tank alk by 0.01 dKH per day.

So the max swing in alk dosing is only 0.05 dKH per day.

 

[Spectre66]

T

Yes. Depending on how you dose and your tolerance for alk changes, the effect may be considered small.

Changing 1% daily, say the water is 12 dKH and the tank is 8 dKH.

That 1% adds 0.04 dKH per day.

When the reservoir has dropped to 7 dKH, we have it depleting the tank alk by 0.01 dKH per day.

So the max swing in alk dosing is only 0.05 dKH per day.

Thank you, that makes alot of sense. I hadnt considered how minimal the effect would be.

 

[Randy Holmes-Farley]

T


Thank you, that makes alot of sense. I hadnt considered how minimal the effect would be.

That's an advantage of the daily water changes as opposed to larger less frequent ones.