New pool owner question

[KS Mike]

I have been lurking since spring and have to start by saying thanks for all you have taught me. I just bought this house and, now 2 year old pool, towards the end of last summer. After opening this year I ordered the TF 100 kit and the pool has been very easy to maintain (thanks to every question I have being answered already).

To make a long story short I have been running the pump about 12 hours a day, with the SWG set at 40-55%. I've only needed to add liquid chlorine during times of high bather load. The last two weeks I have been increasing the SWG cell output and is now at 80%, but have had to add chlorine every day or two to maintain levels.

The pool is covered most of the time during the day, so I don't think UV loss can explain the sudden change. I took the SWG cell out and cleaned it, but it had no scale that I could see.

I began to suspect an early algae problem so I did an overnight loss test the last two nights, which resulted in a drop of 1.5 PPM and 2.0 PPM the second night. The water looks as perfect and clear as water can. I decided to put on some goggles and see if I could find the source. I did find some algae growing on the plastic behind each of the 5 pool lights, and possibly some at a small crack at the bottom of the stairs. I cleaned as much as I could get to with a brush and toothbrush, brushed the whole pool twice, and started a SLAM.

My questions are:

1. Am I doing the right thing or did I jump the gun on going on to a full SLAM?

2. Will the SLAM kill the algae I can not get to? I have a text sent to the builder to find out if I can take the lens off the light, but have not heard anything back yet. There is only 1 tiny screw holding them on, but it looks like electronic stuff behind them (they are LED).

Levels are:

FC 5.0 (before SLAM)
CC 0
pH 7.5
TA 110
CH 150
CYA 70
Salt 3400

Thanks for any advice.

 

[zea3]

Anytime you see algae growing you should slam. How well does your pool circulate water? It sounds like you might have some dead spots that don't see much water movement. Try adjusting your returns to see if you can get better circulation, especially around the stairs and lights.

 

[KS Mike]

Anytime you see algae growing you should slam. How well does your pool circulate water? It sounds like you might have some dead spots that don't see much water movement. Try adjusting your returns to see if you can get better circulation, especially around the stairs and lights.

Thanks for the advice. Glad to know I did not jump the gun on the SLAM. I'll keep after it, and hopefully I can safely pull the covers off the lights and clean them better.

It actually seems to have great circulation, but the light covers are a dome shape that only have about a 1/4 inch clearance between it and the wall. The jets will literally push you across the pool they are so strong. That being said all but 2 jets are on the same wall as the lights.

The stairs are built in flush with the wall and the liner is cut around it with a piece of plastic trim securing it. I was able to brush it pretty well as there is about a 2 millimeter gap at the bottom. Looked like some algae, but might have been a lot of dust and sediment as well. Never noticed it had a gap so I've never cleaned it out.

 

[KS Mike]

I talked with my pool builder yesterday and he gave me instructions on how to remove the lights. Everyone had algae growing in the niche area the light slides into and on the part of the light that goes into the niche. I scrubbed it off, treated a few times with bleach while the lights were out, and left the lights out exposed to SLAM level chlorine for a few hours. Hope it works.

I plan to recheck in a few weeks and if there is any algae, treat the niche area with algaecide and bleach and immediately reinstall the lights. It looks to me like there is little to no water movement around and behind the light.