My pool couldn't survive my vacation

Acuity

Active member
Jun 11, 2018
41
Londonderry, NH
Current water test:

FC: 1.5
CC: 0.0
PH: 7.2
TA: 60
CYA: 40

Following the TFP method I've been using bleach to clean my pool and things have been going wonderfully. When I went on vacation I set up the chlorinator and it worked perhaps a bit too well. Coming back my pool looked green so I ran my tests and came back with a PH of 7.2 but a FC level of around 12. Yikes. I used well water and at the beginning of the year the pool looked green (my iron level is slightly high when the well was tested a year ago), but I managed to filter it out over a few days by putting a few socks in the skimmer. I'm assuming iron is the issue here as well... no pun intended.

So now things get interesting:

I tried my same method, the skimmer sock method, to filter out the iron except this time I got a little more fancy and put a sump pump in the pool to add another pump and thus another sock filter. A good idea that lacked execution. I replacing the socks every couple of hours as well as scrubbing the bottom of the pool with an algae brush and after a few days things didn't appear to be getting better. I perform another water test and find my PH had risen up to a solid 8.0. I've never seen PH rise without adding something to the pool so this kind of baffles me — I assume that this is why things seemed to be progressively getting worse. The only thing I can think of is that the sump pump was somehow aerating the pool.

Fortunately I have muriatic acid on hand (31.45%) that I've diluted and poured into the return jet. I've tried to push it down just a little each time, testing a couple of hours later, and then adding more. Odd thing is my readings are always higher than they should be. I was at at a PH of 7.4 yesterday and added 3 cups of muriatic acid which should've brought me down 7.0 but when I got home this afternoon I'm only at 7.2. Either way I'm trying to push down to 6.8 since I've thrown in the proverbial towel and resorted to ordering Mineral Out and I'm hoping that my FC will hit 0 around that time. I've never used this stuff before but in my reading it sounds like it's suggested that my PH be around 6.8 and FC at 0 beforehand.

When this adventure started about 4 or 5 days ago the water was much more of a darker teal color. Now what I'm looking at is more yellow. Here are some pictures of what I'm dealing with (I dusted off the top step for comparison):


I rang out one of my socks into a measuring cup to get a closer look:

I'd appreciate any suggestions based on what I'm doing and/or planning on doing. I'm still only about a year into owning a pool and am just kind of winging it based on what I've read on TFP. Please let me know if I am missing anything. Thanks for any feedback.
 
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Fast7

Well-known member
Aug 8, 2018
180
Plainfield, IL
This looks to me more as an algae bloom than iron. It would also explain why skimmer socks aren't helping. You can't filter out algae, you have to kill it. I would SLAM the pool.
As for your pH, initial test was lower because pucks caused it to drop some and with FC over 10, pH test is invalid anyway.
 

Acuity

Active member
Jun 11, 2018
41
Londonderry, NH
This looks to me more as an algae bloom than iron. It would also explain why skimmer socks aren't helping. You can't filter out algae, you have to kill it. I would SLAM the pool.
As for your pH, initial test was lower because pucks caused it to drop some and with FC over 10, pH test is invalid anyway.
I initially wrote off algae as the problem because when I left the pool was crystal clear and FC was 5.5. It wasn't until I put the chlorinator into play that the FC skyrocketed and I started to see green water, that eventually turned into yellow/brownish water. To my knowledge my FC has never been below 3 since opening the pool. Stranger things have happened though — I think you might be on to something.

I'm a little hesitant to slam now because I'm in range of being able to use metal sequestrant and it has taken almost a week for the chlorine to get down low enough. I might bring a sample to the pool store tomorrow to see if my problem is actually metal.
 

Acuity

Active member
Jun 11, 2018
41
Londonderry, NH
If it's really algae, you need to deal with it before dealing with any metals in your water.
Do OCLT test, to confirm it's algae.
I did another FC test before going into work and it came out to 1.0 PPM FC with a CC of 0. The tests were done 15 hours apart and there was still sunlight exposure on the pool towards the end of the day yesterday when I ran that test.
 

frogabog

Gold Supporter
LifeTime Supporter
Jul 16, 2010
2,833
Portland, Oregon
What was your test last night? Was it 1ppm, same as this am?

Just a little confused since your last test was 1.5ppm FC, but that was when exactly? You've added no chlorine since that test? Or is your SWG still on? You can't do an OCLT with the SWG running.
 

Acuity

Active member
Jun 11, 2018
41
Londonderry, NH
What was your test last night? Was it 1ppm, same as this am?

Just a little confused since your last test was 1.5ppm FC, but that was when exactly? You've added no chlorine since that test? Or is your SWG still on? You can't do an OCLT with the SWG running.
Sorry for the confusion.

My previous test was done 3:30 PM EST yesterday (when my first post was made) and registered 1.5 PPM FC. The 1.0 test was done around 6:30 AM this morning. It wasn't exactly an OCLT test as I usually run OCLT after the sun passes over the pool, but it still did pass.

I had added no chlorine to the pool since this time as I've suspected metals being the issue. Fast7 made me question my thinking, but the OCLT test makes me think it's metal related again. I have added no chlorine to the pool since this time, and I don't have a SWG. The chlorinator that I have uses the trichlor pucks and it had been emptied and is turned off. No chlorine should've found its way into the pool in the last several days.
 

frogabog

Gold Supporter
LifeTime Supporter
Jul 16, 2010
2,833
Portland, Oregon
So... the problem is that metals do two things normally. Iron will cause brownish stains, and copper is green but it's usually a more brilliant green than your pic shows. It's also not usually a cloudy green.

How much algaecide with copper have you put in? If you haven't put in a significant amount, there's no reason to expect it's copper.

I think you're looking at algae. With no brown/tan staining you shouldn't have an issue with high chlorine and can raise to SLAM level and see what your testing and OCLT shows after that. I think it's algae because that's what it looks like. I might be wrong, but hopefully others will chime in soon.
 

atx

Member
Sep 3, 2014
7
DFW, TX
Get a 5 gallon home depot bucket and put about 3 gallons of pool water in it. Pour half gallon of liquid chlorine in the bucket and mix. If it gets more clear you need to slam your pool. Pour it back into the pool when done.

If it gets worse start a thread for metal problem. There are experts here who can help with that.
 

Fast7

Well-known member
Aug 8, 2018
180
Plainfield, IL
You might have an issue with metals in your water but you definitely have an issue with algae. That one picture with water from rang out filter sock is clear indication for me. Your FC were to close to 0 to count it as passed OLCT. It must be at least 3 ppm to start with and normally it’s recommended to raise your FC to 20% of your CYA. In your case it would be FC 8 to start OLCT
 

Fast7

Well-known member
Aug 8, 2018
180
Plainfield, IL
Additionally, for CYA 40, your normal FC target should be 5-7 ppm and never below 3 ppm. You are letting it drop too low to prevent algae from taking a hold.
 

Acuity

Active member
Jun 11, 2018
41
Londonderry, NH
So... the problem is that metals do two things normally. Iron will cause brownish stains, and copper is green but it's usually a more brilliant green than your pic shows. It's also not usually a cloudy green.

How much algaecide with copper have you put in? If you haven't put in a significant amount, there's no reason to expect it's copper.

I think you're looking at algae. With no brown/tan staining you shouldn't have an issue with high chlorine and can raise to SLAM level and see what your testing and OCLT shows after that. I think it's algae because that's what it looks like. I might be wrong, but hopefully others will chime in soon.
Here's a picture of the stain it's leaving:


This is the top step of the pool with the left side cleaned off. The right side is kind of a greenish brown color. I haven't put algaecide in the pool per TFP recommendations.

Get a 5 gallon home depot bucket and put about 3 gallons of pool water in it. Pour half gallon of liquid chlorine in the bucket and mix. If it gets more clear you need to slam your pool. Pour it back into the pool when done.

If it gets worse start a thread for metal problem. There are experts here who can help with that.
Thank you for your advice. I'm not home right now to run your science experiment, but it sounds like a fun one and I'll try it when I get home.

I forgot to note my my first post that I had run a science experiment of my own when this issue first popped up. I rang out a sock from my filter experiment into a measuring cup and added a fair amount of bleach and stirred it up. The test indicated no positive results but I hadn't paid particular attention to see if things had actually gotten worse. Your test sounds more fun though and I shall try it when I get home.
 

Acuity

Active member
Jun 11, 2018
41
Londonderry, NH
You might have an issue with metals in your water but you definitely have an issue with algae. That one picture with water from rang out filter sock is clear indication for me. Your FC were to close to 0 to count it as passed OLCT. It must be at least 3 ppm to start with and normally it’s recommended to raise your FC to 20% of your CYA. In your case it would be FC 8 to start OLCT
Thanks, so it sounds like what I should do is SLAM the pool. I'm going to try the bucket test first to see how things go but I can SLAM it for sure. The only weird thing to me is that I was at 5.5 PPM FC before leaving, I put the chlorinator online for a vacation, the FC skyrockets to 12 and only then did I start seeing problems. It just seemed weird, but I trust your opinion and it looks like we're going to SLAM.
 
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Fast7

Well-known member
Aug 8, 2018
180
Plainfield, IL
The bucket test mention by @atx is a very good idea. Definitely try that first. As for possible explanation why you might have algae, it’s possible there is dead zone without much water circulation, usually around the steps. It’s possible that water there dropped below minimum and allowed algae to grow.
 

Acuity

Active member
Jun 11, 2018
41
Londonderry, NH
The bucket test mention by @atx is a very good idea. Definitely try that first. As for possible explanation why you might have algae, it’s possible there is dead zone without much water circulation, usually around the steps. It’s possible that water there dropped below minimum and allowed algae to grow.
You mentioning circulation got me thinking. I replaced my 1.5 HP single speed pump with a 1 HP VSP not long before I left. The VSP can run anywhere from 100 to 1000 watts. I'm guessing that I just didn't either run the pump at a high enough speed or for a long enough duration to circulate the pool. The 1.5 HP pump ran for about 6 hours a day and never had this happen. I was running 12 hours a day at 100 watts with the VSP but maybe I should crank that up a bit.

This would explain another phenomena: For a short period of time the water seemed to be improving when I got home. When this happened I ran the pump at half speed for 24 hours. At this time the water was around 12 PPM FC. This was also when I cut off the chlorinator and stopped adding chlorine though. I thought the chlorine dropping was improving the situation (again thinking this was an iron issue), but I think it was the added circulation and constant scrubbing that was perhaps killing off algae. As the pH increased the chlorine started to get less effective (and drop in PPM) the situation only got worse.

In any case, I tried the bucket test and the water looked clear as normal pool water would — thus adding chlorine had no impact either positively or negatively. I added 2 gallons of 12.5% chlorine to the pool and will do an OCLT tonight. Thanks folks.
 

Acuity

Active member
Jun 11, 2018
41
Londonderry, NH
Last night I tested my water at 17.5 PPM FC and woke up this morning with 17 PPM FC. I didn't pass all of the criteria for completing the slam (the water isn't clear). I assume we keep going?

Edit: I my my pool a quick 15 minute scrub down with the algae brush before going into work. I'll do a more extensive brushing when I get home. Yesterday I was brushing the floor and pool walls every hour or two.
 
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