Opening SLAM help ... FC not dropping overnight?

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Bex811

Bex811

Member
May 15, 2024
23
Whitehouse Texas
Pool Size
16750
Surface
Vinyl
Chlorine
Liquid Chlorine
FC 18 CC 0 CYA 45 pH 7.5

Opened pool last week and it was dark green, zero chlorine, zero CYA (1st pic) Balanced pH, added CYA started SLAM.

Got called out of town for the weekend so I added 2 lbs of hypo-cal (generally only use liquid chlorine but didnt want to lose progress while out of town). Got home and water was less green but cloudy (as I expected). FC was at 10 so I added liquid chlorine using pool math.

This morning water about looks the same (2nd pic) but the FC is at SLAM level so no chlorine was used overnight? Would the cal-hypo raise the cya to affect the FC like that? Im currently waiting on a cya test refill so I can't test atm. What should I be doing differently until I can confirm cya level? OR am I just overthinking everything and should just stay the course, continuing SLAM as usual? Thanks!
 

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CYA gets rounded up to the next multiple of 10, so a CYA reading of 45 is rounded up to 50.
SLAM level for CYA 50 is FC 20.
FC/CYA Levels

Is the pump running 24/7?
Are you brushing the entire pool at least once daily?
Have you used a leafrake to scoop out any debris on the pool bottom?

pH test is invalid with FC > 10.
 
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Stay the course. Keep checking your FC level.

Backwash your filter. Good filtering is essential to clearing your pool. Sand filters are the slowest to clear a pool.
 
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ajw22 said:
Stay the course. Keep checking your FC level.

Backwash your filter. Good filtering is essential to clearing your pool. Sand filters are the slowest to clear a pool.
Click to expand...
Good to know! I've just been backwashing when pressure is 20 psi higher than normal. Should I do so more frequently during the slam?
 
proavia said:
CYA gets rounded up to the next multiple of 10, so a CYA reading of 45 is rounded up to 50.
SLAM level for CYA 50 is FC 20.
FC/CYA Levels

Is the pump running 24/7?
Are you brushing the entire pool at least once daily?
Have you used a leafrake to scoop out any debris on the pool bottom?

pH test is invalid with FC > 10.
Click to expand...
Ah! Didn't know to round. Adjusting that now! Thanks so much.

Running pumps 24/7 and skimmingand brushing 2-3x a day. Will check the bottom for debris but had a mesh cover on until last week .
 
Bex811 said:
Good to know! I've just been backwashing when pressure is 20 psi higher than normal. Should I do so more frequently during the slam?
Click to expand...
Backwash when the filter pressure is 25% higher than the clean filter pressure.
 
Day 10 trying to clear up this darn pool! Still slightly green and cloudy with I'm assuming dead algae ... can *almost* see the brush on the bottom when scrubbing. Brushing 2-3x day. Backwashing as needed.

2nd morning in a row that we haven't used chlorine overnight ... haven't dont a OCLT because water is still green/cloudy but I add chlorine to SLAM levels (20) using pool math at night and thats the same reading I get in the morning.

Would using a clarifier be the worst thing in the world if we want to swim this weekend? Or should I tell the kids to deal and keep filtering forever 😂
 

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With that color, I would not have them swim. Also not safe if you cannot see the bottom of the deep end.

How often are you testing and replacing chlorine?
How often are you backwashing?

Sand filters take the longest to clear a pool.

For 10 days in, given your starting state, you are doing good. (just saw your starting state pics in the opening thread).

I assume your CYA is 50. Do me a solid, and retest CYA using this test procedure:
www.troublefreepool.com

CYA - Cyanuric Acid Test

Cyanuric acid (CYA) is the chemical name for the product commonly called “pool water stabilizer” … Read more…
www.troublefreepool.com www.troublefreepool.com
 
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Oh absolutely no swimming until it's clear to the bottom at the very least!

Testing and adding chlorine 2-3x a day. Backwashing when we hit 25 psi up from our normal 12-15. 3 times now but not in a few days.

CYA is at 50. The link posted is how I test! Waiting to get my refill kit to retest. Should be here tomorrow!

I understand sand takes the longest to clear ... I'm wondering if using a clarifier to rush the process is okay or if it'll derail the progress so far.
 

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Donldson said:
Experience tells me there are likely organics in the deep end. Have you taken a leaf net and tried running it around at the bottom just seeing if you catch anything?
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I've run the vacuum robot until nothing comes up in its filter. Brushing with the net doesn't seem to bring anything up and the surface feels smooth with the regular brush. The deepest is the middle where the drain is and I've been extra diligent when brushing around there
 
Before we do anything other than SLAM, I'd like to see some good logs (like how much are you losing), I'd like to see a couple of proper OCLT results, both FC and CC.

So, log all tests and chemical additions, and d a proper OCLT the next two nights.

Ensure you are using your TFP login/password for Pool Math. Go to gear in upper right, scroll to the bottom and "Link from TFP user profile" so we can see your logs.
 
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Bex811 said:
I'm wondering if using a clarifier to rush the process is okay or if it'll derail the progress so far
Click to expand...
Clarifier will cause a gooey mess in the sand filter. You will need to backwash it a lot to remove it. It is not a recommended solution because it adds more complication to what you are already doing with a SLAM.

As you stated, a sand filter takes longer to clear when you have algae. Given that you did not lose any FC over night in your preliminary OCLT you may not have active algae so it is more of cleaning dead algae. Suggest you do a proper OCLT to confirm. Also continue to maintain FC at SLAM level

Have you tried adding some small amount of DE to the sand filter. When you backwash you will remove that so may need to add more.
 
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HermanTX said:
Clarifier will cause a gooey mess in the sand filter. You will need to backwash it a lot to remove it. It is not a recommended solution because it adds more complication to what you are already doing with a SLAM.

As you stated, a sand filter takes longer to clear when you have algae. Given that you did not lose any FC over night in your preliminary OCLT you may not have active algae so it is more of cleaning dead algae. Suggest you do a proper OCLT to confirm. Also continue to maintain FC at SLAM level

Have you tried adding some small amount of DE to the sand filter. When you backwash you will remove that so may need to add more.
Click to expand...
Just the info I was looking for ... Thanks!

So no clarifier, I'll keep on keeping on with SLAM and add some DE to the filter!

Y'all are seriously the best 😁
 
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You have to me mindful that you opened pretty late and it looks like you have a mesh cover. The algae has had a lot of time in good growing conditions to set up a strong colony.

It's going to take time to really crack that, but the chlorine is more persistent than the algae.
 
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