Looking for advice on filter/pump combination

Athlon646464 · May 31, 2022

My pool opens to green every spring. (I have a mesh cover.) I usually SLAM it for about a week (been here at TFP for years) and all is okay, but this year it's been 10 days as of today and very little progress.

Three days ago I started adding DE to my filter and it's helped a little. To try and quantify things by putting numbers on it, 10 being the water at open:

It was stuck at 8 (can't see the outline of the light) until I tried DE, now it's at 6 or 7 (can almost see the light). Normally I can see the light on day 2 or 3 and the bottom on day 4 or 5.

I've always wanted a better filter than sand and pretty much have decided on a cartridge filter - the Pentair CCP520. What should I get for a pump? Do I need a new pump?

By the way, my FC drops only about 2 or 3 in 24 hours - it's been that way since day 5.

Athlon646464 · May 31, 2022

I'm thinking it's the filter because the DE seemed to help - but it's really slow going. I know I could check the sand filter and repair/recharge it, but I've always wanted a better one anyway. Am I crazy?

Texas Splash · May 31, 2022

Unless you have some unusual water demands we don't see in the picture, your current pump will support a new filter. But that doesn't seem to be the real issue here - chemistry is the issue. A new filter isn't going to kill algae, for that you need to precisely follow the SLAM Process page. Your PoolMath test logs haven't been updated since last year, but telling us a bit more about your water chemistry with current test results might help.

In addition, can you confirm what (if any) other products may have been added to the water besides liquid chlorine or muriatic acid? Any other pool store products or algaecides? It may just be algae, but that water sure does have a bright green tint to it.

Athlon646464 · May 31, 2022

@Texas Splash - Thanks for your quick reply! I kinda like the idea of not having to vac to waste and/or backwash - hence the reason for a cartridge filter. I really dislike pumping out what I put in my water - salt and chemicals.

As for chemicals - I've been a religious BBB/TFP follower for years and have been using a TF-100 with fresh regents every year. This year I've only added Borax, liquid chlorine (12.5%) and cyanuric acid. The only time I go to the pool store is for the chlorine and this year for the first time salt (waiting to see the bottom before I add it and turn on the SWG). I had the pool store install the SWG mid-season last year.

Here are this morning's numbers:

FC: 16.5 (was 18 at 5pm last night)
PH: 7.5
TA: 80
CYA: 60
Salt: 2200 (I know it's very low - been pumping a lot of water out of my pool. I have not turned my SWG on yet.) I bought the salt water test kit from TFTestKits.net earlier this year. I get fresh regents every year when they have their March sale.

Texas Splash · May 31, 2022

It's good to know you haven't added anything odd to the water. :goodjob:

So if you were to treat for algae now, you would want to first lower the pH just a little more to about 7.2, then based on your CYA of 60 increase the FC to "24". That's your proper FC SLAM level based on the FC/CYA Levels. Just leave the SWG off for now and use liquid chlorine as the primary agent during the SLAM Process.

As for your rationale of going to a cartridge filer, I understand that as well. That's a big reason I use a cart filter.

Athlon646464 · May 31, 2022

Thanks again. I've been using what is likely the original app on an old ios device since joining here over 10 years ago. It tells me SLAM is 18.

When you mentioned my log I checked for a new version of the app and installed it a few minutes ago on my Android device. I see there it says SLAM level should be 24. I wonder if that will help - gonna go do that right now and continue to use the new app. You noticed that as well - thanks.

Another question - I understand my PH reading may be 'off' because of my very high FC - should I let my FC drop to get my PH in line, then start to SLAM over again at the proper level? If so, at what FC level will my PH reading be accurate?

I'm going to start a new thread on how to install a new filter myself. Even if SLAMing works, I'll likely still want a new and 'better' filter.

Athlon646464 · May 31, 2022

I'm on the verge of 'upgrading' my filter to a cartridge type - the Pentair CCP520. It seems my current pump will work with it.

For the same reasons I'm nervous about removing the multiport valve to check my sand I'm leery of attempting this on my own. Did they leave me with enough room/pipe to work with for either task?

I'm okay with working with PVC pipe as I've done that before, but the pipe next to the multivalve seems very short. How would I even check my sand? The SWG was installed last season by the folks who installed my pool years ago.

Thoughts?