DE Filter pressure readings

[Nursenini]

Hi all!
We have had water in our new pool almost 2 weeks (as of tomorrow). The skimmers are emptied daily, we use hair nets, have a full sun yard with very little debris from the neighbors' trees. Keeping the pool clean has been effortless, so far.
The last 2 days, PB finally did clean up and fill/grading of our yard. After that we had TONS of dirt in my clean pretty pool. I brushed the first evening and circulated the pump on high for several hours (it has been running medium speed for 12ish hours/day) but finally broke out the vacuum yesterday (plastic head, plastic wheels) and vacuumed then brushed and left the pump on high for a couple hours. After this, it occurred to me to check my filter pressure to see if I needed to backwash. I was told by the startup guy that the pressure gauge in the red zone with the pump in medium speed is the indicator for backwashing. My reading for that criteria is about 12, so no worries there. However, on high speed my gauge reads in the red at about 22. On low speed my gauge reads below the green.
Should I be concerned about the pressure at the high and low speed?
Here's some pictures to help clarify:

Pump on high


Pump on medium



Pump on low

 

[pooldv]

It isn't uncommon for the filter to clog in new construction. Always check your psi on high speed and use that to know when to backwash. Backwash it and note clean pressure on high then backwash when the pressure rises 20-25% above clean pressure.

 

[Nursenini]

Thanks, pooldv. Unfortunately I am out of time to backwash this evening. Got grandkids birthday party to go to and no new DE to add...I'm a bit scared to backwash as I only got a quick verbal of instructions and no demonstration...
I work the next 3 days, also...

I posted my latest test results in my build thread as a response to your response from last week. I thought I was doing well but now I think maybe I was testing wrong...
Can you give it a look if you have time?

Should I be posting chemistry separately in the testing and balancing forum? I don't want to double post and get in the dog house, but I also don't want it to get lost...

 

[Jimrahbe]

It won't hurt anything the way it is, but what I believe you are supposed to do is take a reading when the filter is clean and the pump running at some known speed. (Say, 2,000 RPM for example) Then, to check to see if the filter is dirty, you always measure at that known speed (Again, 2,000 RPM). It makes sense to make this measurement when the pump is running in a medium to high speed mode, as at low speed it would be hard to tell the difference between 3 pounds and 4 pounds. So, if the pressure was 10 psi at 2,000 RPM, then you should backwash (in theory) at about 13 psi.

In my case, I never backwash. Since, like you, I have a vs pump, I run it most of the time on a very low RPM so the pressure is down to 1 or 2 psi. I break the filter apart twice a year (May and Oct) and do a complete cleaning. Other than that I rarely even look at the psi gage.

Jim R.

 

[pooldv]

It is definitely ok to wait a bit, nothing will break or explode.

I would do the PSI check at 2500-3000 rpm.

Here are a couple of Pool School articles to help
Pool School - Maintenance and Cleaning of Pool Filters
Use and care for DE filters

I will go move your chemistry questions out of your build thread and into a new thread. I'll pm you a link in a bit.

 

[Nursenini]

Sorry, dv! I just replied to your pm before reading this!
Thank you for all that work moving those posts! And THANK YOU for the reassurance that I won't break my filter or explode anything! I was having some seriously awful dreams and thoughts in my fitful sleep last night!

- - - Updated - - -

Thanks for the advice, Jim!

I guess I need to figure out pump run speeds this next week. Full work weekend ahead, so no time until Monday at the earliest.