Sand filter failure

[Old Eagle]

I am willing to try cleaning the sand but don't know what to do. I put in a good amount of laundry detergent and left it for 2 hours and then backwashed it out but the filtration still is nothing. Even though the pool is now quite cloudy, the filter back pressure has not gone up in 6 hours of running. You spoke of channeling. How do I undo that? Maybe I should replace the sand. This is stopping a lot of swimming.

[CarlD]

Laundry detergent? No, no, no, no, no! Now I believe you MUST replace the sand (I could be wrong). You may have too little sand as well. Or your filter may have been loaded with sand-blaster sand, rather than pool filter sand.

Changing sand isn't too hard and 50lb bags of pool filter sand are usually less than $10. You'll need to know how much your filter takes: 150 lbs, 200lbs, 250lbs, etc.
You'll have to disconnect and remove the top. If it's a top-mount filter, the whole multi port valve comes off. A side mount valve filter may be different.
You'll need to scoop out the old sand. The tricky part is the laterals, the internal plumbing that looks like an upside-down umbrella. You don't want to damage that as you dig out the sand. Once the laterals are clear, you fold them in (like an umbrella) and lift them out. You'll need to inspect them for damage and replace any damaged ones. Dump out the rest of the sand.

When you are satisfied the laterals are fine, you'll start putting new sand in the filter. There will be molded-in rests for the laterals. Do NOT cover these with sand. Just sand below them. Then put in the laterals, unfold them, and seat them, making sure each is in its rest. Now GENTLY add more sand to cover them, being careful NOT to pour sand down the vertical pipe--Masking tape can cover it for now. Duct tape may stick. Add sand evenly until you've reached the capacity of the filter, and gently level it off. You can pour in clean water to help the sand level, but you DON'T want it moving the sand around.

Before you reinstall the multi port valve, check to see that it's working correctly, that the "spider gasket" isn't damaged, and the O-ring that goes around the valve is good, too. Then you can reconnect it all.
You'll want to run the filter on "Rinse" then "Backwash" before going back to "filter".

However, I asked before and I'll ask again: What is the size of your pump and filter? If your pump is too powerful for your filter, this is all a waste of time. You'll need a bigger filter or a less powerful pump.

Best I can do on limited info.

[Anonymous [GDPR] European in the UK]

Yep as Carl said, laundry detergent, loaded with phosphates! I hope a teaspoon of that didn't make it back into the pool.
It's always a good idea to fill the filter half full of water before commencing a fill. It not only reduces the amount of dust you may breath in but it slows down the impact of the sand on the laterals. Personally I would add course gravel to cover the laterals before the sand goes in.

Backwash the new sand and then rinse....before filtering

[CarlD]

I would only add gravel if the owner's manual calls for it. Otherwise, follow the manual. Pool sand should not be very dusty anyway. Half full with water sounds like a lot to me, but I don't suppose it would hurt. I prefer just adding sand slowly and gently. What's the rush?