How to lower TA so I can add borate

[T-Boy]

I'm trying to lower my TA to 100 so that I can put the borate in hopefully tommorrow. My current readings are as follows:

FC 10 (coming down from a Mustard Algae Shock)
CC .5
PH 7.2 (lowered it from 7.5 this morning)
TA 120 (was 140 this morning)
CYA 40

I have lowered PH and turn my jet up to aerate the water but was wondering if there is anything else I can do?

Also I am trying to use up the rest of my chlorine pucks before switching to using bleach so should I lower TA to 100 (called for when using pucks) or lower to 70 or 80 (which is called for if using bleach)? What is the diferrence?

 

[JasonLion]

If you are going to be using bleach in the long run, you should be working on lowering TA down to between 70 and 90. Lowering TA takes time. You need to wait for the PH to come back up before you can add more acid. That might take hours, or it might take days.

 

[T-Boy]

So just keep my PH at 7.2 and wait?

Also just wondering why TA needs to be so much lower when using bleach.

 

[Ohm_Boy]

Your ph will rise with CO2 outgassing, and aeration will speed this. When the ph gets higher, add acid to lower the TA and ph again, and aerate to raise the ph again. That's the process - Add acid to lower both, aerate to raise ph. Repeat as necessary to bring TA to target.

As for the lower TA w/ bleach, this is due to not using pucks. Trichlor pucks are acidic, and tend to lower ph. Liquid chlorine is virtually neutral, so there is no component to drop the ph as there would be w/ trichlor. Higher TA tends to pull ph up, so if you lower the TA, you lessen the natural tendency of th eph to drift up.

 

[chem geek]

Liquid chlorine is virtually neutral

Just so there is no confusion here, chlorinating liquid or bleach are high in pH and have the pH rise somewhat upon addition to the water, but the consumption/usage of chlorine is acidic so the pH drops back down with the net result that chlorinating liquid or bleach are close to pH neutral (there is some excess lye that causes a pH rise over time, but its low in better sources).