Sand filter not filtering

gabed

New member
Jun 30, 2023
4
Atlanta, GA
Hi all,

We have a small 6000gal above ground pool. It came with a pump and cartridge filter but we upgraded to a 14" sand filter kit to not have to constantly wash out the cartridge.

I was going to buy a filter locally but the pool store near us did not carry something that small so I got a pump/filter combo on Amazon and bought the filter sand locally. It calls for 60lbs of sand filled between half way and 3/4 in the tank. I filled it to 3/4.


The issue that I'm having is that it does not seem to actually be filtering the water. The pump is moving plenty of water through the system. There are two inlets, one is connected to the skimmer and the other has the strainer on the side of the wall. These are T'ed together to the inlet of the pump. The pressure gauge reads 4psi.

I have verified that the valve is in the correct position. This one is simplified from the standard Hayward valves in that it only has Backwash, Rinse, Filter and Winter positions.

I've let it run for 40+ hours and it has had no change on the clarity of the water. The chemistry looks good with the correct chlorine and ph levels, yet the water is murky and unfiltered. The pressure never changes from above 4psi even when the filter has run long enough to need to be backwashed. The pressure is the same in all positions of the valve. In reading about low pressure all indications point to restricted flow but the flow is very good to and through the pump.

When backwashing, the flow is good but the water runs clear like nothing was captured in the sand. You can hear the sand moving around in the tank. Rinsing looks the same.

In an attempt to trouble shoot I removed some sand to get it to the 1/2 way mark. This made no change. I even disassembled the valve to check and see if the seals were good or if it possibly had been assembled 180 degrees out of alignment. But everything looked good and the segments of the valve in filter mode line up with sending the water from the pump to the distributor in the top of the tank and then on the standpipe outlet it is sent to the return to the pool.

Any thoughts as to why the filter is not filtering? Thanks!
 
The chemistry looks good with the correct chlorine and ph levels, yet the water is murky and unfiltered.
This would be our first place to start. What exactly are your test numbers? Please post as follows:

FC
CC
CYA
PH
TA
CH (not applicable)

Let us know which test kit you are using and how you chlorinate the water each day. Let's start there as I'm confident it will result in several more questions shortly.

Welcome to TFP! :wave:
 
I don't have a comprehensive test kit, just a simple OTO kit. Chlorine is at 5 and pH is at 7.5
Since you already did a fair amount of diagnosis, we would next rule out chemistry. It's amazing how disruptive water with heavy organics can be to a filter. In your case, we would recommend performing an Overnight Chlorine Loss Test. It's a great diagnostic tool to see if organics is the issue. Of course this cannot be done with an OTO viewer, you would need a reliable test kit like a TF-100 or Taylor K-2006C. You should consider one of those as part of your daily water maintenance regimen. If you have any questions about them, please let us know.

For test kits see: For lots of great articles see ------> Pool Care Basics
 
Is it possible to backwash the filter too much? I have been doing it at least once a day to see if that helps clear the water and to check its functionality. If I leave it be with some dirt in it does that change the filtering characteristics/efficiency at all?

I'm taking a water sample to the pool store shortly to get some measurements.
 
You should clean/backwash a filter when the filter pressure rises by 25% over the clean filter pressure.
I'm taking a water sample to the pool store shortly to get some measurements.
Realize the forum does not provide guidance based on pool store results. You need to get a proper test kit as discussed above.
 
To follow up on this - patience is a virtue. I just had to wait it out and leave the pump on and things cleared up. The pressure went up on the gauge and the flow slowed after a day and a half. I backwashed it and a ton of nasty water came out. Things are all clear now. I just had to let it do its thing.
 
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