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Thread: Cavitation problem, Help!

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    Cavitation problem, Help!

    So my pool was running fine for several months until last week, had sudden loss of pressure at the filter and rattling noises in the pump basket/ motor area.

    Previously running 22-24mmHG, now it dropped to 5-7/
    OUtput has been less than half of its usual.

    I tried flushing the skimmer suction line with a towel wrapped hose, at the pump end, and water seems to be running fine back to the pool,
    Opened up the motor to check the impeller and its not clogged.
    No breaks in any baskets.

    Also does not have enough backpressure to run the vacuum cleaner line, unless I divert all the output to that extension,

    I tried putting some shock in the skimmer line overnight to see if I could expel any organic material this morning and that was no go.

    I called a pool troubleshooter over to check my lines and he said he couldnt do much more for me after looking at my system, suggested to keep the vacuum running to decrase back pressure and extend motor life.

    I never use the vacuum as I run a pool robot.

    I have a small dribble coming from underneath the pump basket area, but see no obvious cracks otherwise and cant tell exactly where its from.

    Just short of calling roto rooter to scope my intake anything else Im missing.
    In Ground- 25,000gal Plaster/Pebble approx 8-10 years old
    Cartridge Filter,
    Jandy Stealth 1.5 hp Installed at pool build- Single speed
    Solar heating on one story roof,Using test strips for measuring
    Salt Water Chlorinator

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    Richard320's Avatar
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    Re: Cavitation problem, Help!

    Welcome!
    I have a small dribble coming from underneath the pump basket area, but see no obvious cracks otherwise and cant tell exactly where its from.
    If water's getting out, air can get in.

    Smother the pump with shaving cream and see if things improve. The foam will stop up air leaks until it gets sucked in itself. You might see the collapsed area as the foam gets pulled in.

    If it's the shaft seal, that won't work to find it.

    The next possibility is that there is something stuck in the impeller. But an air leak is more likely.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Cavitation problem, Help!

    I tried the barbasol method, it didnt do anything new, I tried to feel if there was a vacuum coming from the pump area, but too scared to stick my fingers in any of the orifices.
    I have attacked a picture of the schematic, there is definitely water leaking from this area, in front of the motor. I took the motor housing off the basket to check the impeller, which wasn't clogged.
    I didnt acutally remove the impeller, as I didnt have a suitable tool to do so. So I'm thinking its a worn seal?


    In Ground- 25,000gal Plaster/Pebble approx 8-10 years old
    Cartridge Filter,
    Jandy Stealth 1.5 hp Installed at pool build- Single speed
    Solar heating on one story roof,Using test strips for measuring
    Salt Water Chlorinator

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    Richard320's Avatar
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    Re: Cavitation problem, Help!

    That would be my guess. Part #5. When mine started leaking, I'd see a squirt of water on startup, but not a whole lot leaking on the ground.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Join Date
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    Re: Cavitation problem, Help!

    replaced the seals, and all the orings, to the valve, basket and pump. Leaks went away, but not the noise.
    Second opinion pool tech told me to replace the diffuser, and that solved the problem,
    the diffusers are a glued two piece and mine became birttle at the joint and broke,
    he said its becoming a growing problem and most of the time, its blamed on in ground line issues
    In Ground- 25,000gal Plaster/Pebble approx 8-10 years old
    Cartridge Filter,
    Jandy Stealth 1.5 hp Installed at pool build- Single speed
    Solar heating on one story roof,Using test strips for measuring
    Salt Water Chlorinator

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    Mod Squad jblizzle's Avatar
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    Re: Cavitation problem, Help!

    Quote Originally Posted by DIGIDOC914 View Post
    most of the time, its blamed on in ground line issues
    What does that mean?
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
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    Richard320's Avatar
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    Re: Cavitation problem, Help!

    Quote Originally Posted by jblizzle View Post
    What does that mean?
    Underground pipes
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Mod Squad jblizzle's Avatar
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    Re: Cavitation problem, Help!

    So, explain how the underground pipes could be causing the diffuser to become brittle and break? ... that is really what I was so ineloquently asking
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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    nedchavez's Avatar
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    Re: Cavitation problem, Help!

    I think he means that, with his symptoms when a diffuser breaks, it is often misdiagnosed as a problem with the inground piping instead of a problem with the diffuser.
    16' x 32' IG vinyl liner w/ hopper bottom (12,500 gal), Single-speed 1 HP Sta-Rite pump, and 300# Cristal-Flo sand filter, TF-100 test kit

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    Mod Squad jblizzle's Avatar
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    Re: Cavitation problem, Help!

    Oh!!!

    I did not follow the causality. Not that the pipes cause the problem with the diffuser, but that the pipes are inaccurately blamed for the symptoms that are actually a problem with the diffuser.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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