DE to sand filter question

[NJPoolside]

Our Hayward sand filter, which is probably 30 years old, suffered a cracked standpipe in August last year, so we replaced the standpipe and laterals and because the sand was over 12 years old, we dumped it and put in fresh sand because it needed to be deeply cleaned anyway. We also replaced the key cover and handle assembly, which I wish I had done sooner.

The pool is under oak trees, and they are not our oak trees to cut, and it would likely kill them if we cut them off at the property line, so we are stuck with them. As a result, the pool is full of pollen, and the new sand in the filter is not clearing it. Last week, we added a cup of DE to the skimmer, 1/4 cup at a time in a bucket of water. The pressure did not budge from 11.5 psi (there's a heater on the pool). I stopped at one cup to be sure. The next morning, it was 18.5 psi. I backwashed for several minutes. No change in the pressure. Overnight it jumped to 21.5 psi. We backwashed several times. No change.

I changed the gauge for a liquid-filled new one. It reads 9 psi. The disconnected gauge still says 21.5. So that was broken.

Do I add a bit more DE? Because the pool is still cloudy with a slight yellow tinge from all the pollen (the catkins were filling the skimmer basket within hours over the past week, but I think they are all done falling). Or just leave it be?


13000 gallon fiberglass pool

 

[ajw22]

Welcome to TFP.

What test kit do you use?

Post your full water chemistry from your own test kit.

Run a Overnight Chlorine Loss Test and if you fail it then you need to follow the SLAM Process

I suspect you have an algae problem and not a filter or pollen problem.

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[C3Cl3N3O3]

This sounds similar to my ordeal; you have to be patient. Have a look at this thread:

My pool cloudiness turbidity test

So, I've been battling cloudy water for the past couple of weeks after opening the pool. I have it reasonably good right now, but I've sort of started obsessing over it. The difficulty with cloudiness is objectively measuring it each day. Here's my system. It requires the water is at least...

www.troublefreepool.com

My experience adding DE to a sand filter is that the pressures are somewhat unpredictable. I add 1 cup the same as you. I don't always see the pressure rise immediately. At first, the pressure would rise from 10 PSI to 18 within a few hours so I had to monitor it. After backwashing and adding another cup, it took a full day to hit 18. Now it has been running for a week without needing to be backwashed. So, the pressure rise indicates that there are still a lot of fine particulates in the water which are being filtered.

You want to pick a high RPM setting like service mode and always check pressures at that same speed.

On one occasion, my pressure crept up to 18 and then settled back down to 15 or so. I wonder what would cause that? Like I said, it can be a little unpredictable. But it is effective.

 

[NJPoolside]

Coming back to say that after I posted, it stopped raining here finally so I could throw the Dolphin in, and when i went to clean it... SAND. So we ordered the part and replaced the standpipe and laterals and the pool is crystal clear overnight.

And the pressure is 11 psi. So I think everything is fine now.

 

[proavia]

You might try putting a hairnet in the skimmer basket to easily catch any pollen.
You can get 100 disposible hairnets for ~ $10 on Amazon.
Saves tons of work in not having to clean/backwash the filter as often.

 

[NJPoolside]

You might try putting a hairnet in the skimmer basket to easily catch any pollen.
You can get 100 disposible hairnets for ~ $10 on Amazon.
Saves tons of work in not having to clean/backwash the filter as often.

Thanks for the idea. So much pollen.