Sand change using a trash pump?

[poolschoolguy]

Hey guys, first time poster, long time lurker

I have a commercial account with seven TR-140C sand filters, and they want me to change the sand in all seven. I told them sand doesn't need to be changed unless it's fouled up somehow, but they have deep pockets and they want it done. I'm looking for ways to save time and energy (and my back), so I thought I'd ask for suggestions from the best pool guys out there!

The pump room is crowded and it's very difficult to get a wheelbarrow in there, but they are providing a dumpster nearby for the old sand. There's room for a shopvac, but that will take forever. I plan to try a special rig that connects to my pressure washer wand, and it uses a venturi action similar to a leafbagger to "suck" the sand into a discharge hose. I've had limited success with it in the past, mostly because it works best with a sand slurry that's at least 50% water.

Has anyone tried to use a trash pump to remove sand in filters? I expect it would need lots of water, so hypothetically I could run the pump to fill the tank? They have vsp pumps, so hypothetically I could adjust the flow rate to match the vacuum rate. They dumpster would be about 50' away, so hypothetically I could run the discharge hose directly into the dumpster, no wheelbarrow required. Hypothetically, am I insane?

 

[crusemm]

At my current job we use pumps like these air operated pumps to load resin into tanks. We make a slurry of resin and water (not sure of the exact ratio) and pump it in. One benefit to our set up is the fact that they are positive displacement pumps and therefore move something every stroke as long as that something is a fluid. If there is not enough water in the slurry, the pumps have seized up before. We are also higher than the tanks we are filling and don't have to "lift" it any distance. My only worries with a trash pump (If we are talking about the same type of pump) is that they are centrifugal pumps and may not flow anything, or not have enough lift, or not enough head to push the fluid the distance you need to move the material. My other worry would be that the sand would infiltrate the seals and cause premature pump failure or premature wear on internal surfaces. You are in effect "sanding" the inside of your pump which could in time wear it out.

Just a thought, and I don't know anything about sand filters so I am just shooting in the dark here, Could you "wash" the sand out, like you do when backwashing DE filters? Maybe go in and remove a retention element and then use pump flow to push the sand to the dumpster?

 

[crusemm]

In this drawing it looks like piece 25 unscrews. Maybe shut off flow, drain, remove piece 25, install a hose with a threaded connection at piece 25 location, start flow and push the sand to your dumpster.

 

[Newdude]

Hey PSG and Welcome !!!

It may be more difficult than just sand. I found the specs online that require

• 650 Lbs of Sand Required (Not Included)
• 275 Lbs of Pea Gravel Required (Not Included)

Good luck and keep us posted.

 

[1poolman1]

You shouldn't need to remove the gravel, just rinse it well. Try one of these to get the sand and gravel debris out; they work like a siphon. You'll have to add hose to the end to get the sand where you want it. A bit expensive but they work. You need to allow a lot of time to do the job and it would be good to have a helper with that much sand. Sand Vac

 

[poolschoolguy]

Thanks, guys! I had the same concern about stopping up the trash pump, so I think I'll abandon that harebrained idea.

crusemm, I've tried opening those drain plugs to remove the sand, but the hole is too small so it sort of "oozes" out and takes longer than a shop vac. Good idea, though!

1poolman1, that Pentair sand vac is very similar to the one I attach to my pressure washer. Same concept, but the PW has way more force. The main problem is you have the PW hose, the wand, and a 1.5" vac hose all going into the filter through a small hole, so visibility is difficult. I'm budgeting 5 days for all 7 filters, so I'll try to update y'all on how it goes.

 

[crusemm]

PSG, my idea was to "wash" the sand out, i.e. under pressure, the same way we empty our tanks full of resin. Connect a hose at the plug., turn on the pump, open the inlet and outlet so the pump doesn't dead head, and throttle the outlet closed to provide flow to your discharge line. If this is a repeat job, and you re-plumbed that connection, it could be a real time save/money maker in the future.