On this beautiful California Monday I was asked to examine a swimming pool filter with a leak.
Typically I find the large tank o-ring needs to be replaced and is dripping out of the band or sometimes the air relief assembly will be cracked (on top of the tank attached to the PSI gauge). Expecting the usual issues I was shocked to when I found the actual tank had ruptured and was squirting water out of a crack.
I see this occasionally on other brands of filters but very rarely do I see it on the hugely successful Sta-Rite System 3 filter tank (I can count on one hand how many times I’ve seen this over the last twenty years- and I’ve seen a lot!) Upon visual I made a u-turn and went for my iPhone for some 21th century video posting of an infrequent event.
The other times I’ve seen this occur were no different from today and the culprit was the same: high pressure on the system (think of high blood pressure in a human). The Sta-Rite Maxi II pump is one of the best and most reliable swimming pool & spa pumps ever made so I quickly noticed that the original motor had been replaced (a clue…). Examining the motor plate confirmed what I suspected: an oversized motor: 1.5 horse power. If you watch the video you’ll see a single story roof with six solar panels on it. Solar panels run best at 5-10 gpm (gallons per minute). Easy math shows us 5gpm x 6 panels is 30gpm. So… this system would run best at 30-60 gpm while a 1.5HP pump is trying to push 105gpm through 2” PVC pipes. Something has to give and has: first the shaft seal failed (typically a hair line crack) which allowed water to travel to the bearings in the motor, which caused the bearings to fail which led to the motor being replaced.
Unfortunately, evidence shows that whomever replaced the motor didn’t take the time or care enough to find a solution as to why a perfectly good Maxi II pump failed. I would have suggested the 1.5HP motor be downsized to 1.0HP at the minimum and ideally 3/4HP. If you read your pump curve charts you’ll see that a ¾ could handle the flow requirements pretty easily.
Now, back to the filter… when all the issues with the motor are occurring the tank is holding up like the brute it is. Neglecting to clean the filter elements regularly and neglecting to replace the elements when they need to be and filter pressure increases even more and then one day a little crack occurs and viola, a filter is ruined.
The solution? Unfortunately this homeowner is looking at having a whole new filter installed (it doesn’t make $ense to buy the bottom tank and elements separately) as well as downsizing the pump (or it will just happen again with time). This situation occurs all too often yet the Sta-Rite System 3 usually holds up anyway, today it died because of high system pressure.
Mike the Poolman
Pool Service & Repair in Folsom, CA since 1995