Persistent mustard algae, closing now, what to do?

[CharleneB]

Hello everyone. This summer has been a challenge with the pool. Had mustard algae once two years ago; last year, no problem at all. This year, I've had three bouts of it. First one in early summer, followed the directions and slammed, up to 30 on chlorine, brushed and cleaned; all good. A few months later here it comes again. Repeated process and as soon as the FC got back to 6, here it came again.

Slammed to 30 one more time and kept FC level at 7.5-8. My local pool guy who helps sometimes thinks that's WAY too high, will seriously/quickly degrade the liner. He also says that if the mustard algae keeps coming back that I should dump half the water and refill, and probably change the filter sand out completely next spring.

What say you wonderful pool geniuses?

Thanks in advance.

 

[ff702]

What test kit are you using to get your numbers?

 

[CharleneB]

The big TFTestkit. TF-100. All new chemicals this year.

 

[Texas Splash]

Charlene, can you clarify the process you used as noted in your first post above please? When you SLAM'd previously, did you actually hold & maintain the proper FC level as noted on the [FC/CYA][/FC/CYA] until you passed all 3 regular SLAM Process criteria "before" moving-on to the elevated MA FC level. Then held the MA FC level for only 24 hrs?

 

[CharleneB]

Yes, I followed the rules religiously! Shocked at 10, less than .05 cc, held overnight, and my water has always been clear. So then Slammed to Mustard algae level. 29/30. Cleaned every inch of it. cleaned equipment and pool toys (threw most of them away), Let it drift back after 24 hours. (which took days). As per first post, two years ago (first bout) was ultimately successful; didn't happen at all last year. Then this, first bout was successful for months. Then the next one, same treatment, came back quickly. Thanks for thinking through this with me!

 

[Texas Splash]

Now that you've clarified a bit, now might be a good time to post a full set of results next chance you get. Will you be closing soon? Also, have you ever done a filter sand deep cleaning?