I am new to the forum and this is my first request for assistance. The following is rather lengthy but I want to include all the details. As they say "The devil is int he details".
I purchased my home 3 years ago and the in ground pool, 10 years old, has function flawlessly. Three months ago it began to take longer and longer for the pump (Hayward Super II) to pull a head of water after cleaning the pump's basket. It would sometimes take 4 or 5 minutes vs the initial 1 minute for the pump to acquire a full head of water and start working properly. The pump is located approximately 4 ft. above the pool’s water level. Recently it has been running normally for 2, 3, or sometimes up to five days and then all of sudden I would find it pulsing. That is 1 or 2 seconds of run time and then 1 second of what sounds like cavitation.
I can turn the pump off for a minute or two and turn it back on and it will run normally for 2 or 3 minutes with no air bubbles in the pump basked and then again start the pulsing action. During the past several month I have observed and done the following:
Preceding all of the above the pump motor went out and it was replaced under my homeowners policy which gave me no choice as to the pool service provider. At that time I upgraded the system to a multi speed pump (US Motors 2EZ Speed - Model EB2977T).
When pump again started pulsing I had my regular pool service provider take a look at the problem and he told me that the main drain, at the deep end, was clogged. Being wintertime the gentleman told me I could run the pool filtration using only the two skimmer ports for water intake. Once again after several days the pump started pulsing.
This past week the pump itself was repaired, again under my homeowners policy, when it completely stopped pumping water. The pool service, a different company then the one who replaced the pump motor, repairman replaced some seals in the pump assembly and replaced a broken impeller. When he changed out the pump's impeller he told me it was sized incorrectly and he replaced it with a slightly larger diameter unit. He said this would increase the volume of water through the pump. This appears to be the case because as the return jets in the pool have shown a substantially increased in the movement of water.
The pump/motor assembly has run normally for the past 4 days and then this morning the pump has started to once again begin pulsging. I can wait a few hours or possible a few days then turn the pump back on and again it may well run normally for any number of days.
~ Pump motor, pump seals, pump impeller (upsized), and pump basket lid and O ring have been replaced.
~ All this time the intake has been from the skimmers with the main drain turned off.
~ Water level in the pool is actually above normal and the clean skimmers show water being drawn into the pump system.
~ When the pump is running normally the pump basked is full of water with no sign of air bubbles.
~ I did notice on only one occasion that when the pump was surging that with each surge there appeared to be a small stream of bubbles rising to the top of the basket. The intermittent stream appeared to originate from the side of the basket, which is against the actual pump intake, not the intake from the pipe leading from the pool.
~ I have recently noticed a very small leak from the pump assembly of the Polaris pool sweeper.
~ Filter pressure is 25 psi. When the pump is pulsating the filter pressure jumps between 25 psi and 0 psi. As a side note I believe the 25 psi is possible on the high side and that the dichotomous filter needs to be back washed. The filter itself has not been disassembled and cleaned for almost 3 years. I had planned on doing it this spring.
~ Typically when the pump is pulsing their are no bubbles in the basket and it is completely full of water.
~ When pulsing if I manually put the pump motor in the low speed mode the pulsing stops and the pump appears to run normally with a filter pressure of approximately 8 psi.
I think I have covered all the pertinent facts. Any assistance regarding this problem would be greatly, greatly appreciated. Thank you for your time and consideration in this matter, it is greatly appreciated.