Okay let me start off by explaining my setup.
First off I need to say I am always having to add acid increaser to my pool. I am doing this once every month ever since I first bought the house. When I was talking to my friend who has a working pool he says he never has to add that and actually has to add a PH lowering powder every time it rains. His thought is maybe something with circulation is causing this. This got me to examine my whole setup.
My pool has a main drain that has 2 drain covers in the deep end of my pool. Then on a separate line there is a single skimmer that is on the side of the pool almost 1/3 of the way from the deep end of the pool (so not centered in the pool but in the middle section, my pool is kidney shaped). Both link to a diverter that then feeds to the pump. From the pump it goes to my DE filter and from there it hits the heater. After the heater I have a secondary diverter that then allows me to pick if I want water to come out of the blade or water to then go to my indexer. The indexer then does the 5 pop up jets in the pool. On the indexer is a pause that will stop the pop-up jets. Somewhere in this line (I am assuming between indexer and diverter) I have a number of small diameter pipes that feed into the sides of the pool for circulation.
My pool is somewhere between 19k-22k gallons in size. I am not the original owner of the house/pool so I don't have all the original documentation and have just gone off online calculators.
Here is my issue. When I take the before pump diverter and have it on full skimmer I get very minor suction. The vacuuming using this picks up only the stuff right under the pole. Also the diverter when on shared between the main drain and the skimmer the tiny suction it has is almost gone. The part that has me perplexed and asking if it really can be the pump is because on the backside of the pump. The diverter between the blade and the pop ups. The blade when opened is just gushing out water. Even when its diverted right between the blade and the popups I still get enough water to make it a good 9 inches out from the wall. Another thing I am noticing though is the circulating water on the coming back into the pool section is not coming out the small pipes at all its really just the blade and the pop-ups (and the pop-ups seem to be a bit weaker than I remember them being). This is when I have it diverted directly between the two options (pop ups or blade).
This occurs even after a backwash. (I had thought maybe it was the filter blocking the waterflow).
This got me to thinking the pump is not working right. I have a Whisperflo Pentair WF-26 1 1/2 hp. I still don't get how to determine feet to head when I didn't install the pool and I have no documentation on how much piping there is I just know that there is about 20-25 feet from the pool drains to the spot the pipes come up by the side of the house so in all this would be about 40-50 feet for the main drain and the skimmer (give or take 10 feet).
Can anyone tell me if my thought process is right about this being the pump and this minimal suction? If so why would enough water come out to go to the blade but not to the circulating piping? Also with the information provided can anyone tell me a good comparable pump? I was told by someone if I went salt pool instead of chlorine I should get a new pump type so if it is pump I would like to get one that supports either in case I do decide to go salt in the future. I don't want something WAY too big for the pool but I want something that will allow for circulation and will pull things through both skimmer and main drain.