New filter???

[vtatt]

Hey folks— thanks for all the help along the way.

BLUF:
I keep coming back to green water, fight it for a few days with heavy shock, then it comes back again. Concerned about filter as well, as I usually come back to clumps of green/brown powder on the bottom.

10,500 gal abv grd vinyl
I use pucks plus 73% CH
20 year old 3.22 ft sand filter (changed sand two yrs ago), slightly suspicious of spider valve, but I’m not getting any sand into the pool.
FC 24.5 (shocking now)
PH 7.5
CYA 65?
TA 70

This season has been particularly difficult in keeping the water clean/algae free. I’ve been using the TFP method for quite some time and haven’t had nearly as much trouble as I have this year.

Short story, at the beginning of the season, I get the pool blue and clear, leave for a week and usually come back to a sea of green and Crud on the bottom. I’ve been looking at my filter, wondering if that’s part of the problem, although I know it doesn’t grow algae! I have a sand filter, probably 20 years old. Changed the sand two years ago and it seems to be working well. When I changed the sand, there were no breaks in the plastic bits down below. The spider valve has me a little worried, though, as the rocker arm seems higher than it normally should be.

Should I get a new filter? What am I screwing up with the algae? Any recommendations on type? DE?

 

[proavia]

How are you testing your pool water?

Post a full set of current test results from one of the recommended test kits.
Test Kits Compared

FC
CC
pH
TA
CH
CYA
Water temperature

If you have algae, you will need to do the
SLAM Process
Chances are you keep getting algae because your FC level is too low for your CYA.
FC/CYA Levels

 

[vtatt]

Thanks— yes, using the Taylor kit as recommended. The reason why I put ?? For CYA is it seems difficult to test around that 60 level. I’m also using the SLAM method per the pool math calculator.

 

[proavia]

Thanks— yes, using the Taylor kit as recommended. The reason why I put ?? For CYA is it seems difficult to test around that 60 level. I’m also using the SLAM method per the pool math calculator.

Next time you do the CYA test... and given your CYA of between 60 and 70.

1. Outdoors, bright sunny day with sun high in the sky.
2. Back to the sun.
3. Fill tube to 80 mark
4. Hold tube with two fingers near the top.
5. Lower tube to waist level with tube in the shade of your body.
6. GLANCE into the top of the tube.
7. See the dot - fill tube to 70
8. Repeat 4, 5, 6 above
9. See the dot - fill tube to 60
10. Repeat 4, 5, 6 again
11. Do NOT see the dot - so it disappeared between 70 and 60.
12. Round CYA up to 70.

Remember - GLANCE only. Do not stare while looking for the dot.
Don't try to read between the lines on the testing tube.

Target SLAM level for CYA of 70 is FC 28.

 

[vtatt]

Next time you do the CYA test... and given your CYA of between 60 and 70.

1. Outdoors, bright sunny day with sun high in the sky.
2. Back to the sun.
3. Fill tube to 80 mark
4. Hold tube with two fingers near the top.
5. Lower tube to waist level with tube in the shade of your body.
6. GLANCE into the top of the tube.
7. See the dot - fill tube to 70
8. Repeat 4, 5, 6 above
9. See the dot - fill tube to 60
10. Repeat 4, 5, 6 again
11. Do NOT see the dot - so it disappeared between 70 and 60.
12. Round CYA up to 70.

Remember - GLANCE only. Do not stare while looking for the dot.
Don't try to read between the lines on the testing tube.

Target SLAM level for CYA of 70 is FC 28.

Will-do, thanks.

 

[sktn77a]

Yes, I find it almost impossible to do the CYA test per the Taylor instructions. Rather than a quick glance, i try to use my peripheral vision to determine when the dot disappears.

Not sure why you're having all these issues with repetitive SLAMS unless your CYA is WAY higher than you think it is(?)