Questions about sequestrant and BBB.

[poolcool]

8 days ago I raised CH from 150 to 300 using calcium chloride (peladow) in my 20K gal SWG plaster pool.

7 days ago I performed an acid wash with 10 lbs of citric acid. The manganese stains were removed over night and the next day I added 2 qts of HTH Metal Control sequestrant which is 20%-30% HEDP per the MSDS. I then added another qt of Metal Control the next day to make it 3 qts total. I also added a ½ gallon of HTH algae guard non-foaming formula (10% quaternary ammonium chloride) and another ½ gal the next day.

The pump has been running 24/7 and recirculating back to the pool through a sand filter that I backwashed 3 days ago.

I have slowly brought the pool back to following readings using borax, bleach, cyanuric acid and salt (also added 8 oz polyquat). I was adding bleach very slowly and the FC has been 0 all week until today.

FC 0.5
pH 7.2
TA 85
CH 300
CYA 30
Salt 3400
Borates 15

All testing was performed using Taylor test kits except the borate tests which were made with Lamotte strips.

About 2 days ago I noticed that the water was starting to get a little cloudy. I stopped the pump a few hours ago to see if the water would clear up but it’s still slightly cloudy.

My questions are:

1. Is it possible that there are suspended solids (ex. calcium?) caused by adding too much sequestrant? CH has remained constant all week.

2. Can you have too much sequestrant? Is there a sequestrant test?

3. Do I need to continuously add “maintenance” sequestrant even if I don’t add any water? Aren’t the metals supposed to be removed in the filter with the aid of the sequestrant?

4. I’m ready to add boric acid to bring the borates up to 50 ppm, but I’m concerned now about the slight cloudiness. I was hoping for that “sparkling clear” look. Should I proceed with the boric acid?

5. Should I try backwashing again?

 

[JasonLion]

Some clouding after adding sequestrant is fairly common, though usually it happens several days sooner. This could be that clouding happening late, or it could be the start of some algae. I would try to bring the FC level up a little more, after 8 days that should be alright.

1) That is possible, but it doesn't seem likely in your situation.
2) Yes, but it takes a fair bit to get there. There is a test for Jack's brand sequestrants, other brands may use other formulas which may test differently.
3) You should be adding sequestrant at regular intervals, usually weekly. This maintenance dose should be much smaller than the original dose.
4) I would go ahead and add the boric acid. There shouldn't be any significant interactions.
5) Backwashing shouldn't be needed unless the filter pressure has risen.

 

[poolcool]

Thanks JasonLion.

I saw your post about sequestrant levels up to 5X are OK so I added a maintenance dose of Metal Magic.

The current readings are:

FC 1.5 and rising
pH 7.5 and steady
TA 95-100
CH 300
CYA 30
Salt 3400
Borates 40

I've added almost 8 lbs of CYA since last week so I don't understand why it's not rising faster. I'm using fresh testing reagent.

The pool's still slightly cloudy and I noticed some minor foaming which could be from the HTH Algae Guard I put in last week. Their non-foaming formula might not be as good as advertised.

I'll keep pushing along with the BBB and hopefully the cloudiness will eventually go away.

Thanks again.

 

[JasonLion]

On the CYA, keep in mind that it can take up to a week for CYA to fully dissolve and show up on the test. Also, if you put CYA into the skimmer and then backwash or clean the filter you can lose the portion that hasn't dissolved yet.