high pressure

[Cobo351]

last year was my first year with a pool. Which I bought used, spent the last season with 15-20 psi at the filter. Thinking the sand needed replaced I changed it today with no change in pressure. Its around the same pressure when back flushing, yet I can make the gauge pressure change by using my hand to apply different amounts of "blockage" at the return. and the gauge will go to zero when off. Could the problem be in the valving of the filter?

Thanks,

 

[duraleigh]

I may not understand, but if you were looking for the psi to drop because of new sand, it usually won't. Why did you change the sand?

 

[Cobo351]

Well I guess I thought that the old sand was restricting the flow of water causing the high pressure.

 

[duraleigh]

Virtually never necessary to change sand. If you had let the filter get all clogged up over and over and over til it filled with unremovable debris inside or had calcification from chronic high pH, then maybe.

In other words you would have to almost completely mistreat your water chemistry for a long time to require sand removal.

On the bright side, it seems like your old sand was well taken care of in that the psi never change even 1 pound.

 

[Cobo351]

ok, so any opinions on what is causing the pressure to be so high?

 

[duraleigh]

That's not particularly high....did it used to run lower?

 

[Cobo351]

thats the pressure its been at in the year i've had it. The lable reads it needs to be backflushed when the gauge reaches 7psi.

 

[duraleigh]

The lable reads it needs to be backflushed when the gauge reaches 7psi.

Perhaps they meant when you notice a 7 psi increase which would make sense. Most all pool circulatory systems operate normally between 10-20 psi.

 

[jblizzle]

Although we recommend backwashing when the pressure rises 20-25% over the clean pressure. If you unsure what your clean pressure is, I would suggest a thorough backwash and maybe even cleaning the sand with a hose as described in the channeled sand article in further reading section of Pool School.

 

[linen]

What size/model filter and what model pump?

 

[Cobo351]

The pump is a Doughboy Power Pak II.
The filter is a Doughboy Media Master Series, high rate sand filter, Model 0-1701-016

I did find through the weathered label to backwash when gauge reads 5-7psi above clean pressure.
it says that max pressure is 25psi, it runs clean just under 20.

I guess maybe I don't have as much to worry about as I thought I had.

 

[linen]

Unfortunately, doughboy chooses their filter sizing poorly (too small) so it is not surprising that the pressure is that high with the small doughboy sand filters (since even the largest at 19in is too small for your pool). The part number you gave is for the valve, do you have one for the filter? If not what is the diameter of the tank?

With that said, if it is working, then you can work with it...you will just have to clean it more often then a properly sized filter.

We would still recommend backwashing when the pressure goes up 25% from the clean pressure.

 

[Cobo351]

Thats good info Linen. Does "Model 1600" mean anything? It does list the size just that it holds 150lbs of sand, filter area is 1.4sq. ft.
Thank you,
Cory

 

[linen]

Yes, 1600 means it is a 16" tank and 1.4 sq. ft. filter as you noted. If you were buying a new one, we would recommend a minimum 3.1 sq. ft. sand filter.

Just out of curiosity, do you know the hp on your power pak II and is it a 2-speed?