Trouble with Algae and CYA

[rickmacc]

I've been battling my pool all season so far. My current readings from the Taylor kit are below:

FC: 20
CC: 0
PH: 7.2
TA: 60
CH: 160
CYA: 90

A couple of weeks ago I drained two thirds of the water and refilled with fresh water so I'm surprised to see the CYA this high again. I've been using bleach and shock exclusively. My auto-chlorinator is turned off and I haven't been using any chlorine tabs.

As it stands, my pool is a milky green. I've been brushing and vacuuming to waste every couple of days and maintaining high chlorine levels to try and kill the algae.

What could cause the CYA to rise so quickly? And, at this point, what should my approach be?

Thanks,
Rick

 

[GuinnessPhish]

The only thing that can cause CYA to rise is adding CYA.

Do you use di-chlor to "shock" your pool? That contains stabilizer. Likewise, tri-chlor (pucks) add stabilizer as well.

Both of these forms of shock can take about a week to show up on the CYA test.

 

[GuinnessPhish]

Oh....forgot to add...


ideally, you need to drain about 50% of your water again, stop using "shock", and start using the BBB method (which essentially dictates you use bleach as your primary source of chlorination, and that you only add things to the pool when you NEED it).

If you don't want to drain your pool, you need to SLAM your pool at FC 35:
pool-school/chlorine_cya_chart_shock

 

[BoDarville]

rickmacc:

I've been using bleach and shock exclusively.

What kind of "shock" are you using? Depending on your answer to that question, that is the only thing that would have caused CYA to rise since the water replacement.

The other possibility is that the CYA prior to the water replacement was well over 100. Now that you know it is below 100 and within the range of what the test will read, I still think you will need to replace another 1/3 to 1/2 of your pool water to get CYA within the ideal range.

At 90 ppm CYA, maintaining the proper FC level to properly SLAM will be difficult. I would do another partial drain & refill as suggested above and then resume The SLAM Process.