SLAM to kill mustard algae - CYA @100. Drain and reduce CYA?

[Egor]

I've been battling mustard alage for the past month without success and after reading the articles at TFP, I know why. I picked up the Taylor 2006 kit and tested last night - here were my results:

CYA - 100 ppm - tested 2x, 2nd time with 1/2 pool, 1/2 tap as recommended by the test kit.
TA - 90ppm
CH - 160 ppm
PH - between 7.2 and 7.4 on the kit.
FC - between 16 and 17 ppm
CC - 0

There was a bit of confusion on the CC test as it was listed *after* the FC test. most of the other tests say explicitly to use the water from the previous test, but this one was unclear - do you start fresh or do you use the water you cleared from the FC test? I did both ways and still came up with 0 (yellow - not pink)

Pool water is clear, but I haven't brushed it in about a week. I vaccummed to waste last week and the alage has started growing again. I'm certain it is alage and not polen.

Do I bring the FC up to 39 or should I drain 1/4, fill, drain 1/4, fill until the CYA is much lower? What is cheaper?

I can get 10-12% Liquid in 2.5 GAL jugs from a store locally and I'm curious as to how much I need to add.

Thanks for the great site, looking forward to getting the pool clear and "trouble free".

 

[jblizzle]

Welcome to TFP!!!

The CC test is done with the resulting water from the FC test.

I would recommend lowering the CYA before you continue the battle.

Use PoolMath to calculate the dosages for you.

Please add your pool details to your signature as described HERE as it will help us help you in the future.

 

[Egor]

Sorry mate - when I posted the check box for "Show Sig" was unchecked. Fixed

What is the desired CYA level? There is an automatic chlorinator and pucks are being used.

I used pool math and found that I need to replace 60% to get down to 40.

 

[Egor]

I'll start the drain/refil this afternoon.

My assumption is that I should re-test everything before starting the SLAM - how long after the water replacement is complete should the pool circulate before I test and start the SLAM?

 

[Leebo]

I'd like to start off by welcoming you to TFP! With a bit of work you'll soon have the sparkling water you see in the photo's on the forum.

Given your test results, I would suggest draining your water first to achieve a CYA around 40ppm. To do this, drain 1/4 of the water then refill. Continue doing this until your CYA is at your desired level. The ABC's of Pool Water Chemistry contains a good starting point for clearing your pool's water. After that, the video below details how to "Slam you pool."

There was a bit of confusion on the CC test as it was listed *after* the FC test. most of the other tests say explicitly to use the water from the previous test, but this one was unclear - do you start fresh or do you use the water you cleared from the FC test? I did both ways and still came up with 0 (yellow - not pink)

To preform this test, use the FAS/DPD test rather than the basic OTO test. This video below shows the test using the TF-100, however the instructions are the same as with the K-2006.

 

[jblizzle]

The desired CYA is 30-50ppm. Once you are in that range, you can NOT use trichlor tablets any more and must use liquid chlorine.

Have you discovered Pool School yet? Start with these:
ABCs of Water Chemistry
Recommended Pool Chemicals
How to Chlorinate Your Pool