Hayward S160T Sand filter not filtering properly?

[JesseWV]

I am having some issues with my sand filter's performance.

The symptoms are:

- Pressure never goes above 18 PSI. It starts at 12 PSI after back washing.
- A dense jet of fine dark brown dirt comes out of the return when switching the pump from low to high after a day of run time on low.
- When adding DE to the sand filter through the skimmer a moderate amount of it immediately comes out of the return.
- Lack of water clarity. Fine particles can be seen floating when a sample is taken and held up to the sun.

Other information:

- Last year I took the sand filter apart to clean the sand. Upon opening it I found the standpipe had a piece broken off at the very top where it entered the multi-port. I replaced the broken portion of the standpipe with a length of 1.5" schedule 40 PVC. The laterals were all intact. There was a small crack on the very bottom of the assembly under where the laterals all connect. I figured since this was at the very bottom anyway and the crack was smaller than the lateral opening size that it wouldn't matter. The sand was thoroughly cleaned and the filter was put back together.

- Last year the gasket in the multi-port was replaced.

- The handle to the multi-port used to spring all the way back up when I let it go. It no longer springs back. I noticed there are some broken pieces of plastic washer type material under the handle.

 

[jblizzle]

First let me say the current recommendation is to backwash after a 20-25% increase in pressure over clean ... for you that means you should backwash by 15psi.

I am guessing it is not going over 18psi as it is full of dirt and when you turn to high speed it pushes the dirt through the sand and back to the pool.

There is a chance that your sand is channeled allowing dirt to pass, but I do not think you get the pressure rise if that is the case.

It also sounds like your multi-port may be allowing dirt past it if the spring has gone bad/broken. I would open it up and find out what is going on in the valve.

 

[JesseWV]

So I took apart the Variflo valve to check things out. The spring works fine when it's not bolted down. After I tighten all the bolts the handle has play in it and is only springy once it's pressed down 2/3 of the way. I did notice that the outer O-ring looked flattened. I just bought a nice new pressure gauge and it reads 14 PSI after backwash. I added 3/4 cup of DE, some of which came out of the return. I'm going to let it run all night. If my math is correct I should be backwashing at 17 PSI. I'll check the pressure when I go to work in the morning and again when I get home.

 

[JesseWV]

This morning at 9am the pressure was 18 psi. I backwashed and the view glass looked milky white with not much visible dirt. I didn't have time to add DE before work. After work 9 hours later the pressure is still 14. I added more DE and will let it run over night again.

 

[duraleigh]

What does your pool water look like?

Can you post test results?

 

[JesseWV]

What does your pool water look like?

Can you post test results?

The water looks amazing apart from some debris on the bottom and a layer of pollen floating on the surface from a recent 50mph wind storm. The bottom wrung of the ladder looks just as clear as the top.

FC: 22.5
CC: 0
pH: 7.4
TA: 80
CYA: 85
Salt: 3950
BOR: 50

I added bleach last week to get it to shock level. I threw some leftover trichlor tablets into a floater all last week to keep it above shock while I'm at work. I also needed the extra CYA since it was only 40. It was at shock level all last week. I pulled the tablets out Monday and tested my CYA. I finished adjusting CYA by adding it directly with a sock in front of the return. Boy it really works well when you squeeze the sock. Looks like I overshot my CYA goal by 5 but I'm not too worried about it. I figure my SWG will have to work a little less per day with direct sunlight exposure until it comes down with water replacement over the summer.

 

[duraleigh]

Well, with your water looking like it does and those good numbers, it certainly seems like your filter is doing it's job. It really sounds like you are simply loading up that filter with dirt/dead algae and need to backwash more often.

I don't have enough info on the time frame, but if this started occurring when you added all that FC, then I think you killed off some algae and that you are simply overloading the filter with dead algae. That psi increase should start to slow down now. The forum has recently switched to suggesting a backwash after a 25% increase in psi so that would be fifteen for you.

I suggest backwashing at fifteen and I have a feeling your times between backwash will lengthen.

 

[JesseWV]

If anyone is wondering why I'm not using the SWG, it's because the water is only 62F.

I plan on turning it on when it gets around 65F which should happen soon. I made a DIY low powered pool heater which uses 240ft of garden hose coiled up on the deck when it's not being used.

As a side note I noticed the grey box of the Intex SWG is always warm whether the power switch is on or off. I wonder if I should unplug it?

 

[JesseWV]

... The forum has recently switched to suggesting a backwash after a 25% increase in psi so that would be fifteen for you.
I suggest backwashing at fifteen and I have a feeling your times between backwash will lengthen.

Looks like my old pressure gauge was slightly inaccurate. The new one shows 14psi clean operating pressure. So that would be around 18psi threshold to backwash. Now if I can just get my wife to do it.