Low pressure on the pump

As some of you have read, I have basically rebuilt the pool that came with my house. In fact, everything except the pool wall itself and the pump have now been replaced, from the electrical system to the liner to the sand floor to the deck to the filter.

Now, I go to vacuum the pool this afternoon (new vacuum head and hose), and I got hardly any suction at all. In fact, I got about 2 lbs. of pressure. My normal pressure is about 9 lbs.

I have a 24" x 52" round AGP, Hayward 220T filter and a Astral pools Sena 1800 1hp pump. Looking at the numbers, I think my pump is too strong for my filter, but that doesn't address the low vacuum pressure issue.

I filled the hose with water before sticking it in the drain, and once I turned the pump back on (only off for a couple seconds - my wife was helping), it didn't take long to notice very low suction.

Am I doing something wrong here? I had to take the pump strainer basket out in order to get the pressure back up, even though the basket was empty.

I also noticed filter media around the edge of the pool. I'm thinking it is time to replace the pump. I was hoping to get through this season with it, but I'm starting to think I'll be buying a new one this week.

For the record, I am considering the following pumps to replace the POS I currently have.

Hayward Max-Flo Pool Pump ( Max Rated) | .5hp - HAYSP2800X5
Hayward Northstar Pool Pump Energy Efficient | .5hp - HAYSP4005NS
Hayward Power Flo II Above Ground Pool Pump | .5hp - SP1750
Pentair 3/4 HP Dynamo 2 Speed Pump

Money really isn't an issue, and I'm leaning toward the Northstar due to its claim of energy efficiency and quietness, or the Pentair due to the 2.6Amp draw on the low speed, but I'd like to get an opinion on these four pumps as well as the one recommended by Ben which is getting increasingly more difficult to find (always a concern when a product approaches the end of its life cycle).

HAYWARD SUPER PUMP MAX RATED 1/2 HP 115V

Low pressure and bad pump would not give you filter media deposits, hmmmm.....
Low pressure from pump after connecting the vac - could be a leak pulling in air somewhere in the vac connections, vac head could be damaged, Have you tried filling the hose by letting the water from the return blast into it and out teh vac head? Might blow out an obstruction that's in there....
Could it be that the seal on teh pump lid isn't perfect, the added strain from teh vac stuff could be forcing the pump to start sucking air around the lid ring.
Addressing filter media deposits - are your hoses connected to the right inlets/outlets on the filter? If so, then it's likely a broken lateral (if it's a sand filter).

Sorry, I confused two issues in one post. The sand in the pool and the low pressure on the vacuum are likely not related.

I had sand in the pool last season, and tried to look at the innards of my filter at that time. Unfortunately, the idiot that owned the pool before me SEALED the sand filter, and there was no getting inside. So I replaced the filter with the Hayward 200T. It is brand new, and we were quite careful about putting sand in the filter. We filled the filter with water before pouring sand in, and then we poured in the sand very slowly.

I think that my pump is too strong for my filter, and that is where I think the sand in the pool is coming from.

The other issue is separate, the low vacuum pressure. The hose and vacuum head are brand new. I filled the hose with water from the return before attaching it to the drain. The pressure was fine before I attached the hose, but once the hose was inserted in the drain it dropped down to about 2 lbs. I could not get the pressure back up until I removed the vacuum hose from the drain, shut everything off, and removed the strainer basket from the pump (even though it was empty). Once I reassembled everything, the pressure went back up to 9 lbs.

With a normal pressure of 9psi, I doubt that the pump is forcing any sand thru the filter. Something else is going on with that.

Now, are you getting air in the pump basket when the pressure drops to 2psi or does the basket remain filled with water (completely)?

Honestly, I don't remember, but I think that there was some air in the pump basket. I can't say with 100% confidence for sure if there was or not.

The reason that I say I think my pump is too strong for my filter is because the S220T Filter is rated at 52 GPM, while the 1hp pump is closer to 60-70 GPM. Even though the pressure is only 9lbs., the flow is higher through the filter than it is designed to take, if I am reading these numbers correctly anyway.

After talking to my wife about all this, we have decided that regardless of the problem with the low pressure, we are going to replace the pump. One other thing that I haven't mentioned is that it has a slow leak that I can't seem to correct. The leak is around where the pump motor goes into the wet end of the pump. It's not much water, but it keeps the fiberglass pad the pump sits on wet.

Are there any opinions on the pumps I have listed in the OP?

I would replace the pump seals before dropping 200 bucks+ on a new one unless there are other things that you know for sure are wrong.
I'm wondering if your inpeller stops spinning (slipping on shaft) when you put the vac to it and the resistence increases....
As for the sand - how long have you had your new filter running, supposedly, they do tend to push sand out until it all compacts nicely, I'd just vac it back in for a while see if it stops. Oops - forgot, you can't vacuum :)

The new filter has only been running for about three weeks.

It's alright. I've bought the Pentair Dynamo 2-speed mentioned in my OP. With as much else as has been wrong with this pool, I don't mind spending the money to do it right. Besides, it will pay for itself since it is only a 2.6 Amp draw on low speed, where it will spend most of its time. Even the high speed setting is only 8.6 Amps. Compared to my current 1hp pump which draws 12 Amps, it'll pay for itself by the end of the season anyway.

With this purchase, the only parts of this pool that came with the house are the metal wall and drain. Everything else has now been replaced.

Basically, I have a new pool. :)

I think you will be very happy with this pump. Don't forget the O-ring lube for the lid over the strainer basket.