stenner pump running for hours by accident. Over chlorinated

anthony21078

Well-known member
Jun 14, 2018
96
Long Island NY
About a month ago I installed a 30 gallon stenner tank with a 50 GPD pump. It has been running perfectly for the past month for approximately 4 to 5 minutes twice a day which is keeping my FC between 7-8 with a cya of 50. It is plumbed into the return line and connected to a kasa smart plug that acts as the timer. I have been very happy with it.

I had some major Wi-Fi problems yesterday that required me to change out one of my Wi-Fi extenders that has the smart plug connected to it. Somehow the settings for the smart plug got messed up and the stenner pump was left running from 4 p.m. to midnight (when I discovered it was still on). During that 8 hour run-time window, the pool pump was only on from 4pm to 6pm. Thankfully the stenner tank was low on chlorine (checked 2 days ago) and my math says approximately 4 - 7 gallons of 10% bleach was pumped into the pool.

The stenner pump pushes approximately 140oz of liquid every 30 minutes. Its safe to say that a minimum of 1 gallon but possibly upwards of 3 gallons of 10% bleach was pumped into the return pipe while the pool pump was off. This would have occurred from 6pm to 8pm and stopped when the bleach level reached the bottom of the strainer in the tank. I discovered the problem around midnight and turned the pool pump on to push whatever bleach was in the pipe/filter/pump through the returns.

I don't know if bleach had backed up and made its way through the filter and possibly into the pump. Other than a super chlorinated pool, is there anything I should be checking or worried about?

I've read the stenner can run dry which it did for easily 4 hours but that's not a problem. I know everyone plumbs their stenner line after the equipment because you don't want high concentrations of bleach running through your pump. Any advice here?

Edit - FC is 32. Pool math says approximately 6 gallons of 10% was added to reach that level. So roughly 4 gallons was added while the pool pump was running and 2 gallons added over the course of 1 hour while the pool pump was off. Leaving about 2 gallons to possibly back up through the equipment and sit for 5 hours.

This is all assuming that the water level in the return pipes and plumbing after the filter stays full when the pump is off. Does it?
 

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cowboycasey

Gold Supporter
LifeTime Supporter
TFP Guide
Jul 3, 2013
4,319
Fletcher, OK
whats the saying, the damage is already done if there is any damage at all.. I do not think you will have a problem from a one time thing, most of the warnings are from it happening daily for years on end....

The FC will come down very fast today and within 3 to 5 days you should be good to go to restart your stenner pump :)
 
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Chasarms

Silver Supporter
May 8, 2020
347
Dardenne Prairie, MO
The chlorine solution is heavier than water. The way your port is installed, the LC would have entered the return line and stood there first while pushing the water out of the lines and, of course, mixing with the water to some degree. Depending on the size and length of the return line, it may have held all of it, or if the return jet in the pool is lower than the injection port, it eventually exited into the pool, and did not back up in the filter.

Even if not, it would have had to completely fill the filter before reaching the pump as it would have entered from the bottom of the filter. Obviously, it was not enough to fill the filter, so the pump never saw it. I would be very surprised if there was any kind of damage to anything other than your wallet for burning through six gallons of LC for no reason.
 
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JamesW

TFP Expert
Mar 2, 2011
20,786
One big risk is if hypochlorite got in the feeder with tabs, which would be really bad.

The pump should never be off when there are tabs in the feeder.

Most likely, the sodium hypochlorite went into the return line and fell down. You might have some bleaching near or below the returns.
 

anthony21078

Well-known member
Jun 14, 2018
96
Long Island NY
whats the saying, the damage is already done if there is any damage at all.. I do not think you will have a problem from a one time thing, most of the warnings are from it happening daily for years on end....

The FC will come down very fast today and within 3 to 5 days you should be good to go to restart your stenner pump :)
FC is down to 21 right now from 32. Right at slam level. Should be able to swim tomorrow

The liner pattern might be effected by that much, but that's probably the extent of any issues. Slight fading maybe.
At the moment the liner did not appear to have any lighter areas. Lets see what develops over the next few days

The chlorine solution is heavier than water. The way your port is installed, the LC would have entered the return line and stood there first while pushing the water out of the lines and, of course, mixing with the water to some degree. Depending on the size and length of the return line, it may have held all of it, or if the return jet in the pool is lower than the injection port, it eventually exited into the pool, and did not back up in the filter.

Even if not, it would have had to completely fill the filter before reaching the pump as it would have entered from the bottom of the filter. Obviously, it was not enough to fill the filter, so the pump never saw it. I would be very surprised if there was any kind of damage to anything other than your wallet for burning through six gallons of LC for no reason.
What you wrote is exactly what I was trying to figure out. Makes sense...thanks

One big risk is if hypochlorite got in the feeder with tabs, which would be really bad.

The pump should never be off when there are tabs in the feeder.

Most likely, the sodium hypochlorite went into the return line and fell down. You might have some bleaching near or below the returns.
No pucks in the feeder for over 2 months. No worries there.