im new to this but we bought a used 21ft round pool got it all set up realized that the pump was bad so we bought a new one 1hp same as the one before it. we set everything up how it should be turn it on and for the first 5 mins its fine it runs quietly and everything seems right then all of a sudden you hear the pressure build up and the water coming out of the return starts moving so fast it makes the solar cover push to the other side or when my kids were inside the pool it was making all there toys float to the other side and stay there. we bought a pressure gauge for it and its not working so i know we have to replace that in the morning and the pump is off now. but i wanted to ask on here what would cause that kind of pressure build up i dont believe there are any clogs or anything everything was taken apart and put back together twice. the floaty thing in the skimmer doesn't really float it just gets stuck down and if i lift it up its like a toilet flushing if i hold it up after 5 mins or so bubbles start coming out of the return... sorry im such a newb

It really sounds like everything is working right, but maybe the eyeball on the return needs to be aimed better. What kind of filter do you have.

Were the old pump and new pump identical? Or just the 1HP part?

There are service factors that could make two 1HP pumps VERY different. And a 1HP pump for above ground can be very different than a 1HP pump for an inground pool.

Just wondering if this new pump is indeed more power than the old.

i believe the filter is a cyclone sand filter, my husband said when you try to point the return down it kind of helps but ive never been in someones pool where it shot out that fast.

the old pump we took to the pool store they told the motor was burnt out and showed us one that he said had all the same specs. the old one was a cyclone and the new one is a hayward sp1580

Hum, two things. From what you have said the filter might not be causing any backpressure on the motor and the pressure gauge might be fine. If that were true two things would occur:

1) The output from the return would have a very high water flow and during high flow the pressure gauge reading would be very low (possibly even near zero)
2) During low flow when the pump is first turned on the pressure gauge reading should be higher than in case 1 above.

It could be because the sand filter is somehow being bypassed, sand is too low in the filter, channeling.... anyone else have any ideas?

Both the pressure gauge and water flow are supporting that within 5 minutes there is no back pressure.

Sounds like the right idea.

What is the pressure gauge reading when you first start the pump and after a few minutes?

it reads nothing, im not sure it even works, its brand new but the needle has barely moved. im gonna try getting a new one today.

I doubt that the brand new gauge is bad. It's probably just indicating what appears to be wrong, no filter back pressure.

Two different pumps, two different operating points. Just because the labels are the same does not mean they are the same. My guess is that your old pump was similar to the Intex pumps that come with many AG pools. The PowerFlo LX is much more powerful pump and will produce much higher flow rates.

Double check that the handle on the filter is in the right position, then try holding your hand over the return to see if you get a pressure rise on the gauge.

bought a new pressure gauge and everything seems to be working ok, the pressure is at 12 and staying at 12 we backwashed the filter and rinsed it and that also seemed to help it. and we bought a new return eyeball that sorta faces down a little bit so that everything in the pool doesnt float to the other side including the solar cover. so far so good.