How to kill sponge in pipe?
 

So I have an over the back closed loop on my tank with a pump located about 30 feet away in the basement. Its been going for about 9 years now and has apparently grown a ton of sponge inside the piping. Every time the pump comes on bits of sponge shoot out and its driving me nuts.

So I can obviously turn off the pump and drain the loop, but whats the best way to dissolve all the sponge and still be able to clear it out and be safe to turn back on once done?

I was thinking vinegar, but Im not sure of what concentration to use since the loop is about 10 gallons of piping.

I would use vinegar and start off with as little as you can do you have a way to flush it out so it wont feed in to the tank?

If it were mine, I'd just replace the PVC. Way easier and probably cheaper than whatever you'd end up using to dissolve the growth.

Why do you want to get rid of sponges, do they cause mechanical issues like drop in flow rate or etc? Because they basically provide you with free and effective filtration, with that much of sponge, you might need to keep an eye on bioload after removing them.

You can use boiling water if the pipes are rated for boiling water temperature. But dont inhale the vapor afterwards as it might have toxic chemicals. After that you can scrape the inside by a long pipe/drain cleaning brush.

Something like this;

https://www.amazon.com/dp/B002C4XFCM...a-314350059250

Don't bother dissolving them. Just get the right sized pipe cleaner, and use abrasion power to remove them.

Replacing the piping and running a pipe cleaner down it are not options. The piping is in a ceiling of the basement, total length of about 80 feet and has too many bends. It would take me two full weekends to replace it all.

As said the reason I want to do this is because every time my closed loop turns on, I get a snow globe effect with bits of sponge. I have TONS of sponge in the sump and tank, I dont need the filtration.

If I let air in the pipes and turn it on the bubbles will break a lot of sponge off and stop the snow for a few weeks but it always starts up again. I did this two weeks ago and the tank was literally snowing for 3 days until I let it settle and sucked all the sponge bits out.

Im just tired of it and I want my water to be clear.

Sounds like time to put in a few access points in the piping.

I have clean outs where the pipes come over the back of the tank, and unions on the pump at the bottom. I can isolate the piping in the tank from the rest of the loop, and drain it independently from the tank.

Take a sponge out of the sump, and use it as a science experiment. Put it in vinegar and see what happens. If it dissolves/weakens/disintegrates...

Take the return plumbing, Isolate it at the bottom, and plug/seal it. Fill it with vinegar. Let it sit for a few hours/days however long it needs. Drain the waste, flush it with water a few times, and should be good to go?

30' away. Thats one heck of a closed loop. Air kills most sponges. That is probably why you get a bunch coming out when you turn it back on. You could probably pump oxygen or ozone through it to kill the sponge completely.

Here's an old trick from a plumber friend... tie about 100' of cord around a wad of scrubber pad. Hold the pad, and feed the start of the cord into the overflow, and let the water carry it until it drops out the bottom. At that point, cut the flow and you can drag the wad of scrubber pad through the pipes using the cord.

If it were me, I would rig up a way to recirculate either acid or caustic. Run some tubing from your intake and return into a bucket. If you have things like vermetid snails in your tank with carbonate based structures that could be lining your plumbing, run muriatic acid. Sodium hydroxide should work pretty well for soft tissue/algae. I'd run both, starting with the acid.

This depends a lot on how your closed loop intake/return is plumbed. You could add some valves and tees to be able to do this depending on access.

And wear goggles/gloves...

Can you send a snake down? It will handle your bends, just don't use one previously used on your house plumbing. Dont need a long one as you can hit it from both ends.

If you can isolate the pipe from the sump and tank, set up a pump in a large rubbermaid bucket with fresh water and muriatic acid. Let it circulate for a day or two then replace the water with fresh to get rid of the acid. I do this every couple of years with my return line which runs 30 feet from my tank to my sump. The scrubbing pad on a line helps in this process as well. I found a large round bristle head that I use. It barely fits in the pipe and does a decent job cleaning it.