Losing Confidence In Slam Process

[Donh]

At the end of April I had some algae and followed the slam process. After about 3 days I passed the 3 criteria (cc .5 or less, pass overnight FC loss test, water clear). I let the FC drift down to normal. A week later I had a small amount of algae. I did the overnight test that evening and the next morning. I passed all 3 criteria even though I had algae the day before.

I posted here on 5/6 and the recommendation was that it was probably a very small amount of algae and to do a slam at a lower FC (15-20) for 4 days. On 5/11 I passed all 3 criteria. I let the FC drift down to normal. Yesterday I again had a small amount of algae. Over the weekend I had some algae on tile grout on approx 15 tiles above the water line that I cleaned up. I increased the FC to 15 yesterday morning and brushed, vaccumed and cleaned the filter. Did the overnight test last night/this morning. I lost no FC, cc is 1 and water is clear. At this point my plan is to stay with the slam at the lower FC through the weekend.

Here are the test results from last weekend
ph 7.4
fc 8.5
ch 550
ta 80
cya 80
salt 3400

Any suggestions are appreciated.

 

[Msch99]

Any place small areas of algae could hide? Niches, ladders, supports etc?

 

[Donh]

I don’t see any areas where the algae could hide.

 

[jgofnj]

Do you have a step ladder in the pool? I often find algae underneath each step itself, you can't see it from a normal angle, you need to look underneath each step. I also sometimes find algae in or around the light bracket. While these seem like small places and unlikely the cause, might be worth checking.

 

[Richard320]

You're either not getting rid of all the algae or you're re-introducing it.

Not getting rid of would be behind the lights or beneath/inside ladders and rails. One example here. Check out pictures.

Re-introducing: Pool cover? Floating toys? Scuzz inside a pool noodle?

When it's all done, you might want to run a higher FC than called for. It won't cost you much with a SWG. .

 

[Donh]

There is no ladder, rail, toys, cover. A noodle is used; it doesn’t look dirty but I will clean it. I will pull the light later today.

 

[aeh0603]

What about under the drain cover or inside the skimmer/around the weir door?

 

[DoubleEcho]

What about under the drain cover or inside the skimmer/around the weir door?

I second this, it's a spot that you may not check often especially when you brush the sides of the pool

 

[Donh]

Pulled the light this morning. Did not see any algae but cleaned it and the area the light sits in. However inside the skimmer and under the lid were very dirty. Cleaned all of that up as well as the door. It seems this may be where my problem was. I will do the overnight test Sunday night and see where things stand. Thank you for your help.