What Might have changed? Never had to SLAM before

[BrianWithAY]

I am a little confused. I have lived in my house for 12 years and only for the last couple years have I been fighting this pool.
20,000 Gallon SWG, attached hot tub, in ground, cartridge filter, Dallas

For years, I would throw a bag of salt in and keep it around 3100-ish PPM
and add acid when the Ph would get high. I probably went 9 to 10 years with a crystal clear pool and only the little 2 column tester.
Never cloudy, never green, never any algae.

Now I can't seem to win this battle. I did the SLAM process and got like 90% complete. It was crystal clear then had to go out of town for a week and a half and it is green again.
there are 211 houses in my neighborhood and I would guess 90% have pools. I do not believe for a minute that all of these people have at some point bought 20 gallons of Chlorinating Liquid and did this process or have ever done it.

I am sure it is a beautiful process that works great when you run it to completion but I have never had to do it before.

Is it possible somehow the chemistry has changed making is susceptible to growing algae now? If I drain it and refill it, It will go back to the way it was?
Something has changed but I am baffled. All my numbers are in the proper ranges, the SWG is working. I even bought a 2nd one just in case.
A week and a half of ignoring the pool and it has algae. There were years when I would go months between testing the water.

 

[Bperry]

I am a little confused. I have lived in my house for 12 years and only for the last couple years have I been fighting this pool.
20,000 Gallon SWG, attached hot tub, in ground, cartridge filter, Dallas

For years, I would throw a bag of salt in and keep it around 3100-ish PPM
and add acid when the Ph would get high. I probably went 9 to 10 years with a crystal clear pool and only the little 2 column tester.
Never cloudy, never green, never any algae.

Now I can't seem to win this battle. I did the SLAM process and got like 90% complete. It was crystal clear then had to go out of town for a week and a half and it is green again.
there are 211 houses in my neighborhood and I would guess 90% have pools. I do not believe for a minute that all of these people have at some point bought 20 gallons of Chlorinating Liquid and did this process or have ever done it.

I am sure it is a beautiful process that works great when you run it to completion but I have never had to do it before.

Is it possible somehow the chemistry has changed making is susceptible to growing algae now? If I drain it and refill it, It will go back to the way it was?
Something has changed but I am baffled. All my numbers are in the proper ranges, the SWG is working. I even bought a 2nd one just in case.
A week and a half of ignoring the pool and it has algae. There were years when I would go months between testing the water.

You know the drill… post up your numbers. If you have algae, it means you don’t have enough chlorine.

 

[BrianWithAY]

You know the drill… post up your numbers. If you have algae, it means you don’t have enough chlorine.

I know my numbers are trash. Here is the thread where I started slamming the pool last month: Were to get stand alone High Chlorine test
A month ago, it was stable because I was working it daily. I want to know why it would be hands off for years and now I have to be on top of it constantly

 

[Bperry]

I know my numbers are trash. Here is the thread where I started slamming the pool last month: Were to get stand alone High Chlorine test
A month ago, it was stable because I was working it daily. I want to know why it would be hands off for years and now I have to be on top of it constantly

It’s likely that the extended drought in that area means you haven’t had the kind of water replacement you normally get. People in the area using chlorine tabs may start finding high levels of CYA building up (without water replacement) and finding that chlorine isn’t as effective, which leads to algae growth. Also possible the extended heat combined with less water replacement contributes even more.

Or you got very lucky for years.

 

[Newdude]

Algae grows with inadequate sanitation. There are no two ways about it. There is one answer and it's always more chlorine.

Your FC levels dipped and you got algae.

The only thing you may see now to prove the how is if your CYA dipped allowing more FC to burn off than you were producing.

I get it that other years were great but no 2 seasons are the same and a wet one or a hot one can foul what the previous plan was.

 

[Mdragger88]

As you said - that was a month ago.
What are your numbers today?
Fc
Cc
Ph
Ta
Ch
Cya
Salt

 

[Jimrahbe]

Brian,

You have algae because you allowed your FC level to get low. Where do you try to keep your FC level? What is your normal CYA level?

I suspect that you have always run your FC much lower than we recommend, and this year your CYA dropped more than usual, and your FC went to zero.

Your SWCG was making enough chlorine to keep it from being a full blow green for a while, and then the algae won...

Do you normally add powered "shock" on a routine basis??

The good news is that in the DFW area you can most likely replace all your water cheaper and quicker than you can trying to do a SLAM.

Thanks,

Jim R.

 

[BrianWithAY]

I figured it out. I suspect 2 years back, I reduced the time running the pump in hopes of saving elec costs. It was only running about 6 hours a day. 2 in the morning and 3 in the evening.
I am running it 14 hours now and the pool is crystal clear. Should have thought of that sooner.

 

[Newdude]

I am running it 14 hours now and the pool is crystal clear. Should have thought of that sooner.

UV demand / daily FC loss fluctuates like a bell curve over the season. You need much less FC daily in the ends of the season, and lots during the peak season.

Ironically, your lower SWG runtime is likely fine now, but it wasn't enough when it was hot out.

Overnight Chlorine Loss Test and make sure you aren't keeping an algae bloom at bay. It'll be lying in wait to explode again at the first hiccup if you don't address it now.

 

[reggiehammond]

I figured it out. I suspect 2 years back, I reduced the time running the pump in hopes of saving elec costs. It was only running about 6 hours a day. 2 in the morning and 3 in the evening.
I am running it 14 hours now and the pool is crystal clear. Should have thought of that sooner.

Considered running a VSP 24/7 at low RPMs? You can make FC and skim non-stop and means you may not have to chase as much as you are doing. I'm using less than 200 watts per hour, so running non-stop costs very little at low RPMs.

 

[Mdragger88]

I figured it out. I suspect 2 years back, I reduced the time running the pump in hopes of saving elec costs. It was only running about 6 hours a day. 2 in the morning and 3 in the evening.
I am running it 14 hours now and the pool is crystal clear. Should have thought of that sooner.

What swcg do you have?
What kind of pump do you have?
Filling out your signature with all your details & posting test results goes a long way in helping us help you unravel your mystery.