Need some help with CYA

[john286]

My analysis:
FC 3
TAC 3
CH 200
TA 90
CYA 99
pH 7.4
TDS 700
Phosphates 300

I have a 40,000 Gallon pool with a hayward NGS60 (60 Sq ft) filter. I recently had a quick algae bloom and being a kind of newbie with chemicals I used one dosage of Yellow Out, which is way under the recommended dose. I did everything it said added correct shock and what not. It was all doing fine until I noticed a weird smell. I checked the chlorine and it was at 0 and Total Chlorine was at like 0.3 or something like that. So the pool guy told me to shock and then a day later backwash. I did all that but then the chlorine was still low so I ended up adding about 9 pounds of shock in an hour without checking the CYA or knowing that the type of shock I am using has CYA in it. I also use Trichlor tablets in an in-line feeder. So now everything is back to normal, but im worried about this so called "Chlorine Lock".... Is this a thing or should I be ok doing what I am doing? I am soon going to switch to the BBB method. But I still have alot of Dichlor shock. Suggestions and ideas please.

 

[Richard320]

Welcome.

Wow...where to begin?

Well, those are pool store numbers, so don't trust them. I'll bet CYA level is well over 100....maybe over 200. Mine was when i started taking care of it myself.

All I can say is: Immerse yourself in

Spend some time reading threads in the algae forum, too. Your story is not unique.

 

[jblizzle]

Welcome to TFP!

Your pool will not stay clear for long with a CYA over 100 and a FC of only 3 ppm.

I agree and suggest you read through Pool School to get an understanding of the chemistry. And order yourself one of the recommended test kits.

You likely should replace a lot of water to get back to a reasonable CYA level. And you can not use the Dichlor as that is what got the CYA high in the first place.

Posted from my Droid with Tapatalk ... sorry if my response is short

 

[duraleigh]

But I still have alot of Dichlor shock.

Welcome to the forum. :lol:. Don't use it now...period. YOu can save it and use it when your CYA is manageable. Using it now is a bit like saying, "Well, I know that chicken is what gave me food poisoning, but I still have quite a bit left so I'll use that up and then start feeling better".

 

[Stuamurr]

but im worried about this so called "Chlorine Lock".... Is this a thing or should I be ok doing what I am doing?

Chlorine Lock is a reasonable description, but not accurate, Chlorine becomes bound to the CYA and it's effectiveness is heavily diminished, which is why it is important to maintain FC as described in Pool School so that the Chlorine Residual does it's job effectively and quickly.

I am soon going to switch to the BBB method. But I still have alot of Dichlor shock. Suggestions and ideas please.

Switch immediately by starting to use Bleach/Sodium Hypochlorite, your tri-chlor and di-chlor can be retained for future use in increasing your CYA when required.

I checked the chlorine and it was at 0 and Total Chlorine was at like 0.3 or something like that

You will need substantial amounts of chlorine to satisfy the chlorine demand of the pool before it settles down again, because all you had at that point was chloramines (combined chlorine) which is where the distinctive smell has arisen from.