Lowering Fc To Safe Level

[mcnico]

I'm down in Austin, TX with an IG plaster pool, roughly 12K, cartridge filter, in-line chlorinator (tabs)and recently experienced algae that turned my pool a mild green color in two days. Realize now that I let the FC level drop after a pool party and heavy rain.

Tried the pool store for a solution but they suggested I buy and apply seven different chemicals at ($185) over a 3 day period. It justed didn't sound right to me so I read up on-line and went with the liquid bleach instead. Now I have what appear to be ultra high levels of FC (off the charts on both reagent test kit and strips) while other levels (PH, CYA, TA) appear to be OK.

I put about 9 gal. of bleach in over a 48 hr period, brushed and ran the pump 60 hrs straight. The water cleared up in two days and looks great now. But I'm afraid the FC levels are unsafe for swimming and may be damaging to my equipment. Any advice will be greatly apprecaited?

Would peroxide neutralize the bleach without further negative affects? Other means of bringing it down faster than just burn off?

[waterbear]

I'm down in Austin, TX with an IG plaster pool, roughly 12K, cartridge filter, in-line chlorinator (tabs)and recently experienced algae that turned my pool a mild green color in two days. Realize now that I let the FC level drop after a pool party and heavy rain.

Tried the pool store for a solution but they suggested I buy and apply seven different chemicals at ($185) over a 3 day period. It justed didn't sound right to me so I read up on-line and went with the liquid bleach instead. Now I have what appear to be ultra high levels of FC (off the charts on both reagent test kit and strips) while other levels (PH, CYA, TA) appear to be OK.

I put about 9 gal. of bleach in over a 48 hr period, brushed and ran the pump 60 hrs straight. The water cleared up in two days and looks great now. But I'm afraid the FC levels are unsafe for swimming and may be damaging to my equipment. Any advice will be greatly apprecaited?

Would peroxide neutralize the bleach without further negative affects? Other means of bringing it down faster than just burn off?

The high chlorine wont hurt anything, don't worry. I suspect that your CYA levels are high from your use of trichlor tabs with a cartridge filter (a surefire recipe for an overstabilized pool!) and that is why the chlorine levels are not dropping fast.

They will eventually come down. I would not recommend chlorine neutralizers since they are often a cure worse than the disease. Overdosing on them can make it very hard to maintain a FC level and most of them are sulfite based. Peroxide will destroy chlorine but, once again, overdosing can be a problem.

You need to get a better test kit such as the Taylor K-2006 or other kit that tests chlorine using the FAS-DPD titration test and also can test pH with acid and base demand , TA, CH, and CYA. FAS-DPD can test chlorine levels up to about 50 ppm with a precision as great as .2 ppm. It is probably the BEST investment you can make in your pool and will pay for itself time and again!

It would help if you could post a full set of test results. The fact that you said the pH appears to be ok when the chlorine is too high to measure is bogus since high chlorine levels will interfere with pH tests and make them read high when they are not. IF your chlorine was really too high then the pH would have also measured too high!

Is your drop based chlorine test one with shades of red or shades of yellow? (strips are useless so we won't even consider them)

If it is shades of red it is a DPD test that measure FC and TC and can bleach out at high chlorine levels (as can strips) leading you to believe there is little or no chlorine when it is high.

If it is shades of yellow then it is OTO which only measures TC but does not bleach out.

In either case you can get a rough idea of how high the chlorine is by diluting a sample of pool water with distilled water and testing that as follows:

1 part pool water 1 part distilled water and multiply your test results by 21 part pool water 2 part distilled water and multiply your test results by 3

1 part pool water 3 part distilled water and multiply your test results by 4

1 part pool water 4 part distilled water and multiply your test results by 5

Please post a full set of test results. I am particularly interested in your CYA readings.

[mcnico]

The high chlorine wont hurt anything, don't worry. I suspect that your CYA levels are high from your use of trichlor tabs with a cartridge filter (a surefire recipe for an overstabilized pool!) and that is why the chlorine levels are not dropping fast.

They will eventually come down. I would not recommend chlorine neutralizers since they are often a cure worse than the disease. Overdosing on them can make it very hard to maintain a FC level and most of them are sulfite based. Peroxide will destroy chlorine but, once again, overdosing can be a problem.

You need to get a better test kit such as the Taylor K-2006 or other kit that tests chlorine using the FAS-DPD titration test and also can test pH with acid and base demand , TA, CH, and CYA. FAS-DPD can test chlorine levels up to about 50 ppm with a precision as great as .2 ppm. It is probably the BEST investment you can make in your pool and will pay for itself time and again!

It would help if you could post a full set of test results. The fact that you said the pH appears to be ok when the chlorine is too high to measure is bogus since high chlorine levels will interfere with pH tests and make them read high when they are not. IF your chlorine was really too high then the pH would have also measured too high!

Is your drop based chlorine test one with shades of red or shades of yellow? (strips are useless so we won't even consider them)

If it is shades of red it is a DPD test that measure FC and TC and can bleach out at high chlorine levels (as can strips) leading you to believe there is little or no chlorine when it is high.

If it is shades of yellow then it is OTO which only measures TC but does not bleach out.

In either case you can get a rough idea of how high the chlorine is by diluting a sample of pool water with distilled water and testing that as follows:

1 part pool water 1 part distilled water and multiply your test results by 21 part pool water 2 part distilled water and multiply your test results by 3

1 part pool water 3 part distilled water and multiply your test results by 4

1 part pool water 4 part distilled water and multiply your test results by 5

Waterbear,

Thank you very much for the reply and advice. I apologize for not including more accurate data in earlier post. I've just returned from the local pool store with latest test results. They seem to confirm what I'm getting from both strip and OTO testing at home.

FAC = "6" But the manager there suspects it was more like 8 but his test kit only goes to 5 (?)

TAC = 6

CYA = 50

TA = 100

pH = 7.4 (He also had concerns about this result since the FAC was so high)

He also suggested I let it burn off rather than try to neutralize it for the same reasons you stated. I actually performed a test using 1 gal. of pool water and a capful of peroxide this AM and WOW did it do a number on the chlorine level!

I looked at two test kits (Leslies brand) but was unsure of which to choose. One was $43 the other $69 but both seem to be capable of same tests. One had larger chamber for pH test. I will take your advice and invest a suitable kit like the Taylor K=2006.

Is there a better alternative to the Trichlor tabs? I like the in-line chlorinator for convenience because I travel during the week and can't always test 3-4x/week.

Major thanks again for the help this forum provides us newbies!