Persistent Cloudy Water - Day 6 of SLAM

[chris87]

I have been helping my new neighbor with getting his pool ready. I’ve used the TFP method for years on my own and have had great results. He has an above ground pool (approximately 10,000 gallons) with a sand filter. My pool is a cartridge filter, so I’m not as familiar with sand. What is surprising me is that there is a residual cloudiness that doesn’t seem to be going away. Mine usually clears up quickly, even when the water is green at opening. I’m not sure if it will eventually clear, and I should just keep slamming. Overnight loss was 3.5, so we are getting closer. Is there anything that I need to do with the filter? Is it possible there is an issue with the sand? I read on another post about someone adding DE, so I don’t know if that would help. I appreciate any tips, suggestions, etc.

TA: 70
pH: 7.4
CYA: 55
FC: 25
CH: 100

 

[zea3]

Sand filters are great for the convenience of cleaning. A sand backwash is a quick and relatively pain free experience compared to breaking down a cartridge filter and hosing it off, but it does have its drawbacks. The biggest one is how slow it is to clear debris from the pool. The only time you will notice is during a slam. In a clean pool you probably won't notice a difference in filtration quality. I used to use a small DE filter that had to be broken down and hosed out multiple times a day during initial days of a slam, it would clog so fast. Since I didn't see a change to my natural laziness preventing the pool from going green over the winter, I got a sand filter. Easier and quicker to clean, but longer to clear the pool.
You can help the clearing process by adding a little DE to a sand filter after every backwash. That will trap finer debris generated in a slam.

As far as test results, There is no 55 marking on the CYA test cylinder and the gradations between levels are not linear. A CYA result that is more than 50 and less than 60 should be read as 60 and that value used to generate the FC target for the slam. Will your neighbor consider replacing some water to lower the CYA to 30?

 

[chris87]

Sand filters are great for the convenience of cleaning. A sand backwash is a quick and relatively pain free experience compared to breaking down a cartridge filter and hosing it off, but it does have its drawbacks. The biggest one is how slow it is to clear debris from the pool. The only time you will notice is during a slam. In a clean pool you probably won't notice a difference in filtration quality. I used to use a small DE filter that had to be broken down and hosed out multiple times a day during initial days of a slam, it would clog so fast. Since I didn't see a change to my natural laziness preventing the pool from going green over the winter, I got a sand filter. Easier and quicker to clean, but longer to clear the pool.
You can help the clearing process by adding a little DE to a sand filter after every backwash. That will trap finer debris generated in a slam.

As far as test results, There is no 55 marking on the CYA test cylinder and the gradations between levels are not linear. A CYA result that is more than 50 and less than 60 should be read as 60 and that value used to generate the FC target for the slam. Will your neighbor consider replacing some water to lower the CYA to 30?

Thank you! This was very helpful. I actually looked again with the sun out, and there is definitely improvement. Probably 25% better than yesterday. Like you mentioned, it’s just very slow. At least compared to my cartridge filter. I will keep slamming until it passes the overnight loss test. I have a feeling he will not want to lower unfortunately. He already did a partial drain to get the CYA to the 60 mark. I will definitely make sure he uses LC and not pucks for normal chlorination.

 

[pypeke]

I don't know if this will help, but I always add 1/4 cup of diatomaceous earth (for pool!) to my sand filter. Search for D.E. on this site to see how to use it.

I have about 16,000 gallons in my in ground pool. I have learned that if I open my pool at the end of April before the weather gets too hot, it is much easier to SLAM. It is also cloudy and rainy in April to mid May, so I seldom have to add chlorine. I only have algae on the pool cover's center windowpane. The rest of the pool is clear. 2 days of slamming is all that is needed with 69° water.

If I wait until the end of May, the water is about 75-80°, and the pool looks like a swamp. Then it takes 10-14 days to clear it. This last week we have had lots of rain and it has been very cloudy. I still had chlorine in the pool after 7 days of rain. Not even close to swimming weather yet, but at least I don't have a swamp. Good luck.