My first algae bloom...

May 19, 2016
129
St Catharines, Ontario, Canada
Pool Size
95000
Surface
Vinyl
Chlorine
Liquid Chlorine
I started using the TFPC method this spring when I replaced our liner, and had a fresh fill. I noticed late last weekago my pool was getting a bit cloudy. I had recently change my pump time from 18 hours a day down to 6 hours, and attributed the cloudiness to not having my filter on long enough which was probably a rookie mistake. During this time I also let my FC drop to 2 ppm a couple of hot days in a row, basically because I was riding the lower range of my FC. A few days ago I noticed a bit of green on the deep end slope of the pool, but couldn't tell at the time if it was algae or a reflection because it was windy that day. I continued to keep the FC between 3 and 5 and the CC was always at 0.

I had to go a way a few days and had my wife add the required amount of bleach to keep it in the range. Today I returned to a fine layer of green on my liner, and am assuming it is algae. Here are my test numbers when I returned.

FC 3
CC 0
pH 7.8
TA 100
CH 125
CYA 35

I pretty sure I need to do a SLAM even thought my CC is 0 because I have visible algae, but want to check before I proceeded. I am lowering my pH now to get it in slamming range in anticipation of beginning a SLAM and have the robot out cleaning.

Please help as I have never done a slam, nor have the experience to know I need to do one.

Thanks.
 
Hi Steve! :wave: You got it .... SLAM. :) Round-up your CYA as 40 and SLAM at an FC of 16 and you're on your way. The SLAM page link is below in my sig. Just follow that page and keep your FC at 16 and you should see great improvements. Make sure to maintain that FC of 16 until you pass ALL 3 SLAM criteria. Good luck!
 
Well, its unfortunate but it does sound like you were playing with fire and it burned ya.

That FC was too low for a CYA of 40 (there are no half way numbers).

Get some liquid chlorine at hand, and your pool brush and get to work! It may go quickly if you get on it fast. If you think you're going to run out of testing reagents from the frequent tests during a SLAM order them now!

I hope she :queen: keeps you in a cute Speedo while you brush that pool :bowdown:
 
Brushed and bleach, looks better already.

I assume the brushing helps the filters remove the dead algae so I brushed it a few times.

My FC is currently at 16. Will check again in the morning for OCLT, and to maintain the FC of 16. Have the filter on full and running 24 hours.
 
Phew...survived. Past the OCLT test this morning with a less than 1ppm drop in FC. My CC is zero, and water crystal clear.

Question is what is the safe level of FC for swimming now that I have finished my slam with a CYA of 40? It's getting hot and I know there will be swimmers lining up. Thanks
 

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Dead algae should be more of a grey/white color, the live stuff can be any shade of green, black, or yellow depending on the stage and severity. Live algae you might be able to scrape of grab some and smear it on paper. Other light algae will simply "puff-up" in a light plume of dust.
 
Thanks for the answer. The reason I asked is I noticed a gray cloud when brushing my liner and assumed it was dead algae that my filter hasn't picked up yet from my SLAM. I am going to investigate adding DE to my sand filter but I wanted to get the sanitizing part down first, before I ventured into the more complex.
 
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