Green Stuff

[Tdubya]

I noticed some light green stuff on the spa seat today when I was testing the water. The chlorine level on the generic ph/chlorine tester showed the content to be .5-1. We’ve recently received a bunch of rain the past weeks. After adding 10% bleach and letting the pump continue to run for about an hour, I did a drop test and came up with 4ppm. I used the brush to clean away the green on the seat. The water has been between 74-78 the past few weeks and it gets close to full sun all day 9:30-7 or so. The pool is new to us (2 months in) and we’ve used the spa almost every weekend since we moved in. The water is crystal clear as always.

These are the numbers from the most recent tests

PH 7.5
TA 60
CYA somewhere between 34-42 since it’s so subjective (viewing in direct sunlight versus shade)
CC 0
CH 375

 

[Tdubya]

Here’s a pic of a corner that still has a spot. Also, I run the pump at 2000rpms for about 14-15 hrs a day.

 

[Texas Splash]

Good evening! It sounds like you have algae. The FC was definitely too low compared to your CYA as seen here FC/CYA Levels. I don't see an alternative other than to start a SLAM Process.

 

[justinc]

Dallas area home depots seem to have some fresh 3 gallons/box 10% liquid chlorine. Should clear it right up. If you buy 4 or more boxes you get it for $2.99 a gallon. Should fix you right up!!!

 

[Tdubya]

Thanks for the replies. I’ve started my first SLAM this evening. I lowered the ph to about 7.2 and brought up the FC to 16.5. I was shooting for 15 but either my cya or gallon capacity are slightly off.

 

[Tdubya]

I’m guessing I tested for FC too soon after pouring it in last night (25-30min) because this morning the reading was 18ppm.

 

[Texas Splash]

I’m guessing I tested for FC too soon after pouring it in last night (25-30min) because this morning the reading was 18ppm.

Perhaps, or maybe the estimated pool volume isn't quite as large as anticipated. Once you do this a few times you'll see a pattern. If you use PoolMath correctly, and dispense the prescribed amount of bleach required and it still goes high above your target, then your pool may be a bit smaller than first thought. It can also work the other way around for some folks.

 

[Tdubya]

I believe the algae may be in the lights in the spa and pool. Is there a way to clean in there or will the SLAM eventually kill it all? Last night the CL dropped 2ppm and it was the same the first night.

 

[justinc]

I believe the algae may be in the lights in the spa and pool. Is there a way to clean in there or will the SLAM eventually kill it all? Last night the CL dropped 2ppm and it was the same the first night.

You need to scrub and brush as much of the crevices as you can while your chlorine level is high to break up the algae and expose it to the high level of chlorine so it will die. Algae can sometimes form a film which protects it from chlorine which is why the scrubbing and brushing is necessary to expose it.