Single return in pool has no flow

[dpl252]

New pool/homeowner here (pool in signature) and just finished doing a SLAM, will post chemistry at the bottom but I had a new Intelliflo VSP 3HP pump installed, everything's been working great but because I had bad algae when I moved in I couldn't see the pool much at all. Now that it's clear and I can see everything I noticed there's a single return in my pool that has no flow.

When I turn the pump on, I think it self primes at a high RPM, all my returns shoot out some bubbles and then have a good flow once the pump slows a bit, but this one return just gurgles out small bubbles for like 30 seconds and then nothing. I'm including a video to show the behavior. The video starts right after I turned on the filter so you can see the small bubbles, and then right after it ends, no flow out of the return at all. All other returns in both the pool and attached spa have good flow.

https://imgur.com/a/Ks66Onj

Any ideas on how to troubleshoot? I'm guessing the line is clogged somewhere....

FC: 4
CC: .2
PH: 8.2
TA: 150
CH: 360
CYA: 30/40

(my PH is high from SLAMming so i'm treating It today with acid)

 

[Texas Splash]

Your pH is not high from the SLAM anymore. The FC of 4 is low enough. Time to hit the pH with some muriatic acid. Since your TA is on the elevated side, I would lower the pH to about 7.2. Each time you lower the pH from 8.0 to 7.2 it will help lower the TA a bit. Be mindful to watch that FC and not let it drop too low as noted on the FC/CYA Levels.

As for the return, good video upload. Perhaps an obstruction. To give us a better idea of everything, can you post some pics of your equipment pad so we can see everything?

 

[dpl252]

Sounds good! I also saw some other posts where people recommend lowering ph to 7.2 and then aerating to lower TA. I had waterfall features which I'm guessing aren't the best for aeration, I also have a small 1HP sump pump which I saw someone would put on their shallow steps and tilt towards the pool to make a fountain affect, I may see if I can set that up after lowering PH.

I had made a previous post with a bunch of pool equipment pictures, I hope it's okay to link that thread instead of re-uploading everything here, if not I can definitely re-upload!

New pool owner trying to make sense of pool plumbing - also issue with return jet

Hello TFP! Just bought a home recently with a 23,000 gallon fresh water, in-ground plaster pool. I knew nothing about pools and inherited this one with the purchase. To add to it, the previous owners let it go a few days before we took possession and then we were out of town for 2 weeks...

www.troublefreepool.com

 

[Texas Splash]

Aeration doesn't lower TA, it increases pH. Sometimes people do that (aeration) to expedite the pH rise so they can use acid again sooner (8.0 to 7.2). If you run your waterfall a lot, it certainly can increase the pH. I would recommend minimal usage of the water and do the pH-acid drill to lower the TA down to about 50-60. That should help reduce how fast the pH rises.

 

[dpl252]

Aeration doesn't lower TA, it increases pH. Sometimes people do that (aeration) to expedite the pH rise so they can use acid again sooner (8.0 to 7.2). If you run your waterfall a lot, it certainly can increase the pH. I would recommend minimal usage of the water and do the pH-acid drill to lower the TA down to about 50-60. That should help reduce how fast the pH rises.

Gotcha, Pool Math says to lower ph to 7.2

Should I lower more than that and then just run my waterfalls to gradually bring it back up to swimmable levels?

 

[Texas Splash]

No, you don't want to go down too low which would make the water aggressive/corrosive. Just do the acid routine in phases and eventually the TA will begin to fall.

 

[JamesW]

The pool has really bad copper and iron stains.

Do you have a heater or ionizer?

 

[dpl252]

Are you sure it's copper? I just ordered jack's magic stain identifier because i'm not sure what the stains are (there's actually a bunch of different stains)

You're referring to the tan colored stains below the water line and not the white stains above? The white stains, I assumed were from calcium and I tried doing some light acid washing and that didn't help at all.

No ionizer, we have solar heat for the pool and gas heater for the spa. My understanding is that gas heaters can add copper to the water, correct?

 

[JamesW]

The black and green are copper.

The yellow and brown are probably iron and maybe silver.

Maybe the previous owner used copper and/or silver algaecide.

The copper heat exchanger has probably corroded some.

The heater might have cast iron headers that are also corroding.

Check the headers with a magnet.

If you want to clean it, sulfamic acid (Jack’s #2 copper and scale stuff) is the only thing that might work.

After the treatment, I would drain and refill if it is safe to do so without floating the pool.

You want to get rid of the copper and the sulfamic acid.

You might be able to take the TA down to zero to help the process if the sulfamic acid is not completely effective.

Sulfamic acid and low TA are corrosive, especially to copper, so there are risks associated with the treatment.

You want to take the equipment offline to avoid contact with the corrosive water.

If your ground water is high, the pool can float, so you need to control the water before draining and refilling.

 

[dpl252]

Gotcha that is helpful to know! I sadly just drained about 70% of the pool and refilled before slamming, so the stains either existed before I moved in or it's in the water source already and my shocking oxidized the metals.

Will Leslie's test for metals if I bring them a sample of my water source (municipal water, not well water) to get an idea if it's coming from the water or if it maybe was due to algaecides? I don't think my Taylor tests for iron/copper...

Here are some more close ups of the stains. I can also see what appears to be a trail which i'm guessing is from when the previous homeowners did an acid wash....



I may wait until winter to treat the stains considering I just paid $300 to refill most of the pool but really appreciate your advice!

 

[dpl252]

As another follow up, looking for suggestions to diagnose or treat a clogged return (I'm assuming it's a clog in that line since all the other returns work just fine)

 

[JamesW]

Will Leslie's test for metals if I bring them a sample of my water source (municipal water, not well water) to get an idea if it's coming from the water or if it maybe was due to algaecides?

Municipal water won't usually have a lot of copper.

Pool stores can test for metals, but we have very little confidence in their testing.