First time backwashing, did I do it right?

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thecabana

Member
Jul 24, 2022
22
Austin, TX
Hello! I'm a new pool owner of a previously built in ground pool, ~17000 gallons. For the first 2 months we lived in the home, I hired a pool company to help take care of the chemicals and equipment so we could settle in. They cleaned our Hayward DE filter at the end of May/early June. They have no record of backwashing since then, so I don't think they did. So I backwashed today.

I have a variable speed pump. This morning when I looked at the pressure before backwashing, it was
10 psi at 1500 rpm
25 psi at 2755 rpm
32 psi at 3200 rpm
35 psi at 3450 rpm

I was advised to measure the pressure at 3000rpm+ and also backwash on that speed.

So I backwashed and rinsed a few times until the water cleared up. Recharged with DE. Unfortunately I lost more water than anticipated so had to add water, help the pump prime, bleed some air from the filter. That all seems to have worked okay and pump and filter seem to be working well. DE seems to have recharged okay. With all of that, the pressure at 3200rpm went down from 32psi to 26psi. Did I not backwash enough, or is 26psi an ok clean pressure? I'm so afraid of messing up the equipment 😫
 
thecabana said:
Hello! I'm a new pool owner of a previously built in ground pool, ~17000 gallons. For the first 2 months we lived in the home, I hired a pool company to help take care of the chemicals and equipment so we could settle in. They cleaned our Hayward DE filter at the end of May/early June. They have no record of backwashing since then, so I don't think they did. So I backwashed today.

I have a variable speed pump. This morning when I looked at the pressure before backwashing, it was
10 psi at 1500 rpm
25 psi at 2755 rpm
32 psi at 3200 rpm
35 psi at 3450 rpm

I was advised to measure the pressure at 3000rpm+ and also backwash on that speed.

So I backwashed and rinsed a few times until the water cleared up. Recharged with DE. Unfortunately I lost more water than anticipated so had to add water, help the pump prime, bleed some air from the filter. That all seems to have worked okay and pump and filter seem to be working well. DE seems to have recharged okay. With all of that, the pressure at 3200rpm went down from 32psi to 26psi. Did I not backwash enough, or is 26psi an ok clean pressure? I'm so afraid of messing up the equipment 😫
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The best way to know if your numbers are good is to completely teardown and clean the filter, add the required amount of DE, and record starting pressure at a speed you will use as the benchmark. A 6psi drop after a backwash might be a good number for your system. Every pool is different.
It is good to remember to only add about 80% of the DE capacity to a filter that has been backwashed and not torn down. Backwashing never removes all the old DE.
 
1poolman1 said:
The best way to know if your numbers are good is to completely teardown and clean the filter, add the required amount of DE, and record starting pressure at a speed you will use as the benchmark. A 6psi drop after a backwash might be a good number for your system. Every pool is different.
It is good to remember to only add about 80% of the DE capacity to a filter that has been backwashed and not torn down. Backwashing never removes all the old DE.
Click to expand...
Okay thank you that's good to know and very helpful! So the main speed I'll use is where I'll want to measure/benchmark it, not the highest speed? It runs at 1500rpm for about 6 hours and 2755 for about 6 hours on a schedule.

Yes - I think to completely start over my filter needs 7.5 scoops of DE and I put 5 scoops in after backwashing, does that sound about right?
 
1poolman1 said:
record starting pressure at a speed you will use as the benchmark.
Click to expand...

thecabana said:
So the main speed I'll use is where I'll want to measure/benchmark it, not the highest speed? It runs at 1500rpm for about 6 hours and 2755 for about 6 hours on a schedule.
Click to expand...

Just choose a speed and use THAT speed for your baseline pressure and to check you current pressure. Needs to be the same speed for both measurement. Doesn't have to be run speed, but it can be. Just don't use a low RPM, it won't show a pressure rise.

I have a pentair Superflo VS. My top speed is 3450. I happen to choose 3000 to check my baseline and current pump pressure. I run my pump 24/7 at 1400. After I backwash, I run the pump to 3000 and note my pressure. Every week or so, I run my pump up to 3000. If my pressure has risen 25% over my baseline pressure, I backwash. At 1400, It doesn't move from 6.5psi, at 3000 it shows the resistance of the dirt in the filter.

You could choose 2755 for your "filter pressure check" speed, would make it easier to check, never have to fiddle with the pump.

Hope that makes sense!
 
Oh, and WELCOME TO TFP!!!! :wave:

Joining Welcome Home GIF
 
thecabana said:
Yes - I think to completely start over my filter needs 7.5 scoops of DE and I put 5 scoops in after backwashing, does that sound about right?
Click to expand...
Hayward filters require 1 pound of DE per 8 square ft. of effective filtration rate for clean pre-coat. After a backwash use 80% of that number. 5 - 6 scoops sounds about right if 7.5 is your clean pre-coat amount.
 
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PoolStored said:
Just choose a speed and use THAT speed for your baseline pressure and to check you current pressure. Needs to be the same speed for both measurement. Doesn't have to be run speed, but it can be. Just don't use a low RPM, it won't show a pressure rise.

I have a pentair Superflo VS. My top speed is 3450. I happen to choose 3000 to check my baseline and current pump pressure. I run my pump 24/7 at 1400. After I backwash, I run the pump to 3000 and note my pressure. Every week or so, I run my pump up to 3000. If my pressure has risen 25% over my baseline pressure, I backwash. At 1400, It doesn't move from 6.5psi, at 3000 it shows the resistance of the dirt in the filter.

You could choose 2755 for your "filter pressure check" speed, would make it easier to check, never have to fiddle with the pump.

Hope that makes sense!
Click to expand...
This is very helpful!

This may be a silly question, but what speed do you run your pump for backwash & rinse?

And thank you for the welcome! I already am really appreciating all the resources on TFP!
 
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