New Salt System, algae is recurring regularly

[CarlD]

With an SWCG, the FC level must be at least 5% of the CYA level to MAINTAIN sanitation.

The BBB method and an SWCG are NOT different systems. BBB is a methodology, a system YOU practice.
SWCG is simply a way to introduce chlorine into your pool, continuously. No more than that.

You should be always using the BBB method. BBB stands for "Bleach, Borax and Baking Soda" but that's really only a quickie shorthand for the principle of testing your water religiously, and adjusting it as it needs it. Daily simple Chlorine and pH testing lets you get ahead and stay ahead of problems. An SWCG can make it so you don't have to do so much, but it's just making it easier.

But now you have algae so you should either turn the SWCG off or pretend it's not there, and use plain old bleach or liquid chlorine to dose your pool up to the shock level indicated for your CYA level, and keep the FC level there, testing 2-3 times a day, and adding bleach/liquid chlorine to raise it.

Let's get the algae killed first, then worry about the pH, and finally, after that, adjusting your SWCG to be optimal.

[jhk49]

Well, I certainly learned somethings today. I didn't realize that you could go back to bleach once you had gone to a salt system. The CYA is presently at 32. What level of chlorine should I reach to shock the pool and for how long do I need to hold it?

As suggested, I will get the algae bloom taken care of and then address the output level of the salt system. I am presently running the pool pump at the summer time levels of 10 hours per day. I think I can drop it to 6 hours per day and provide a FC range of 3.0 to 6.0.

Thanks for the continue support.

Jim Kempf
Leesburg, GA

As my Pennsylvania Dutch Grandmother would say, "Too soon we get old, Too late we get schmart."

[CarlD]

There's a lot to learn, Jim, but it's not really all that tough.

Pool care (water maintenance) comes down to 2 1/2 things:
1) Sanitation: That's chlorine to kill pathogens and break down bio matter
2) pH: How acidic or alkaline your water is.
2 1/2) Stabilizer to determine the proper level of chlorine.

Total alkalinity is mainly a buffer for pH, once you've eliminated obvious causes for its rise or fall. After that, if pH is rising too much, you generally lower TA. If pH trends down, you raise TA.
Calcium Hardness is useless in vinyl pools unless it's too high, then scaling can happen. In masonry pools (concrete, tile, etc) sufficient calcium in the water helps keep the calcium from leeching out of the walls.

For correct stabilizer levels, see the "Best Guess" table:
http://www.poolsolutions.com/gd/best...ine-chart.html

Not sure how you got a CYA # of "32". I presume you either got it from a pool store or guessed at it.

Normally, for a CYA of 30 to 50, we suggest a shocking level of 15ppm for your FC (free chlorine), and, generally, a maintenance level of 3-6ppm.

But you have an SWCG system and those usually require a CYA level of 60 to 80ppm. Correspondingly, with an SWCG, an FC level of at least 5% is recommended, which would be 3 to 4. But you CAN go higher if you need to. I generally do.

BTW, I use the BBB method and have an SWCG--an Autopilot. Remember: SWCG stands for salt water CHLORINE generation, and in your pool, chlorine is chlorine. All of us who have SWCGs occasionally supplement with other chlorine forms, but most usually bleach/liquid chlorine.

[SunnyOptimism]

I'll chime in since I'm a pentair IC40 owner. The Pentair manual says max CYA of 50ppm but ignore it. 60-80ppm is the range you want. I run at 70ppm and that works great for my pool.

[jhk49]

We have had a rainy last few days here in south Georgia, but I have managed to add cyanuric acid to the pool so as my latest readings are as follows: CYA 70, pH 7.4, FC 8.2. I have disconnected the IC40 and have added 484 fl. oz. of 8.25% bleach. This should raise my FC to 20.0. I will check all chemicals tomorrow mid-day. Then my plan is to vacuum the pool as required, reconnect my SWCG system and decrease my pump running time to about 8 hours per day (it had been running at 10 hrs per day. It is cooling off in my area to about a high of 75 and lows in the mid 50's. Any comments on the plan would be most welcome.

[SunnyOptimism]

You need to check your water chemistry more frequently in the beginning of the process. Once you add the bleach, check it again in 1 hour to see if you're at the correct level. Even in clear water with a possible (but not visible) algae bloom, your FC will drop very rapidly in the beginning as the chlorine oxidizes biologic and organic matter. I'd be willing to bet a bottle of bleach that your FC will not be 20ppm in 1hour.

Other than that, good plan. You can actually keep running the IC40 during the process, the high FC level won't hurt it. You only need to shut it off when doing an overnight chlorine loss test.

Oh, and only check FC at this point. The phenol red pH test doesn't work at FC levels greater than 10ppm.

[jhk49]

As to my "guesstimate" of an FC of 20, it was based on the internet pool calculator that I have used numerous times with good results. Based on what I added 484 fl. oz. of 8.25% bleach and a starting FC of 8.2 the new level should have been 21 ppm. I did this at about 11:30 am, it is now 3:28 pm and I rechecked the FC as you recommended .... it came out to be 22.5 ppm. Instead of the bleach, how about a another bottle of chlorine titrating reagent (R-0871).

Be that as it may, it has been sunny but relatively cool down here in south Georgia, maybe that has something to do with it. I will continue to check and thanks for your confirmation of my approach and the tip that I can leave my SWCG system on.