Fc from 6.5 ppm to 0 ppm

RESISTENCIA13

Well-known member
May 21, 2015
157
Scotch Plains, NJ
Pool Size
33000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 700
I need some assistance. My FC just dropped from 6.5 PPM TO 0 PPM within 24 hours. There has been no rain, my heater is off, etc The only thing I did was to add a stain remover yesterday morning. Could the stain remover cause such a drop on FC? or could it cause false reading? Please help....I do not know what to do.
 
Hi!

I used 2 lbs of Pool Stain Treat by United Chemical. It does not list any chemicals, but does not mention anything about reducing chlorine. It does mention that it could lower the PH levels. My PH was 7.9 prior to adding the pool stain treat and now PH is 7.5.
 
That would be Oxacilic Acid and it is exactly what dropped your FC level. Before doing strain treatments it is highly recommended to allow the FC level to drop (and potentially add a polyquat algaecide to prevent algae during the treatment) because they will just react with each other. Oxacilic acid is also less optimal than Ascorbic acid because of the possibility of it reacting with calcium in your water, forming Calcium Oxalate and clouding it up.

Here are instructions on AA stain removal. Keep in mind that the purpose of AA treatment is to remove the stains, the metal will remain in the water and need to be sequestered unless you change a significant portion of the water.
Ascorbic Treatment to rid Pool of metal stains
 
Pool stain treat is oxalic acid and will reduce chlorine. Bring the chlorine back up slowly and carefully. Don't shock as that can cause the metal stains to drop back out. Add a quart of poly 60 algaecide and a quart of good sequestrant.
 
My pool was built last year. I do not know when the Spa was stain. I just noticed it a few weeks ago. Attached is a picture of one dotted stain and the rest is just the walls being yellowish. I have never add any algaecide to my pool.

- - - Updated - - -

Well....I still have the stains.

I would think that if the stain remover you added works, that's a good indicator that the stains were metal.
 
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