Pool is very difficult to balance.

[Lambchop]

I have an in ground pebbletec pool with attached infinity spa and rock water fall, approximately 14,000 gal. I have a 2 year old Pentair Whisperflow, 2HP pump and a Pentair cartridge filter system with four Filbur FC1978 cartridges that are 1 year old and were cleaned one month ago. I clean them every three months. Pool has a Hayward Pool Vac with a dedicated vacuum line. The pool also has a regular skimmer and a QuikPure Ozone System. The pump runs 9 hours per day, every day of the year (daytime). I use only liquid chlorine and liquid acid. I brush the pool at least three times per week and manually skim almost daily. Both skimmer baskets checked at least every two days. Water hardness here is quite high. Pool was drained and refilled two years ago, including an acid wash. Last summer I used an inordinate amount of chlorine.

The pool always seems to be on the edge of going green. I see green tinges on the walls and the clarity is not the best. Last summer I was always jockeying between high pH and low alkalinity, fixing one and then messing up the other. Seesaw at its best. In one day, the pool can go from looking really good and clear and then, not so clear with green tinges showing here and there. I'm not sure why my pool water is so fragile all of a sudden.
Last year, in frustration, I "slammed" the pool over a three day period. No change. I would hate to drain and refill again but I'm open to anything at this point.

I have a TF100 kit and the results are as follows:
CYA=60
TA=100
pH=7.2-7.5
CL=1.0
Hardness=750
FC=25 ppm
CL=0

What am I missing? The pool man I used to have used nothing but Chlorine tablets and the pool was always stunning and that's before my new pump and new filters. I'm about to surrender...lol.
I must be missing something here.
Thanks for any help.

 

[Rancho Cost-a-Lotta]

When you say you "slammed" the pool, did you follow TFP SLAM Process guidelines? With visible algae, you need to move forward with a SLAM. With green patches growing on the walls, I would follow up with the mustard algae removal process as well. Your FC is already elevated, it's a good time to start.

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I suspect you never really got rid of the algae, which explains what you describe as excessive FC loss and reoccurring outbreaks.

As far as a water exchange, your CH is elevated, but manageable...for now. Unless you top off with softened water, I assume your fill water is high in CH. With evaporative top-offs, you'll need to exchange water by the end of the season or risk scaling.

Probably not the news you wanted...

 

[Rancho Cost-a-Lotta]

Just took a closer look at your test results. FC 25...is that right? You have CL listed twice. What is CL?

 

[Lambchop]

Yes, I followed this sites Slam process. CL is the chlorine reading from the test kit. Says 1 for Cl and 2 for Bromine, from the Taylor K1000 basic test kit. FC is correct, 50! drops to get to clear.

 

[Rancho Cost-a-Lotta]

FC is correct, 50! drops to get to clear

Got it. So that was a 10mL sample, correct?

Don't worry about the K-1000 "OTO" chlorine test. It doesn't provide the accuracy required to maintain your pool.

 

[Jimrahbe]

Lamb,

Something is not at all right... I really doubt you have an FC of 25 and yet a test with the OTO (color match) only shows 1 ppm

You never need to run the OTO color match test if you plan on testing your FC. I personally never use the OTO test.

Do you use a speed stir or are you swirling by hand?

How old are your reagents?

In your location, you should be using a Saltwater Chlorine Generator (SWCG). No more lugging chlorine, just let the salt cell make the chlorine you need.

I suggest that you run another test and double check your FC reading.

If your FC were at 25 ppm, your OTO test would be off the scale dark red or purple and not 1.

Please let us know what you find out.

Thanks,

Jim R.

 

[Lambchop]

From what you're indicating, I guess it is slam time again. That mustard algae must be the culprit. When I see the green tinge and brush the area, it is a greenish yellow color that comes off. I never suspected more than just plain old algae due to an imbalance of chemicals.

 

[Lambchop]

I swirled the chemicals. It was the 10 ml test. The chemicals are older, I'd guess five years? Too old?
I store inside at room temps.

 

[Lambchop]

Btw, I did two FC tests because I was at the 45 drops point (still bright pink) and thought I must have done something wrong, so I tossed that. Rinsed the container and re-did the test and arrived at the 50 drops to get to clear.

 

[Rancho Cost-a-Lotta]

5 years is probably too old for reagents. As Jim mentioned if your chlorine level was that high, the OTO test would have been off the charts. You were reading it at 1 ppm. Have you added several gallons of chlorine lately? You can do a test for FC on your tap water and see what it shows.

 

[Jimrahbe]

Lamb,

I have never used 5-year-old reagents, but anything over 2 years old is suspect.

In order to have an FC of 25 ppm in AZ, this time of year, you would have had to have added over three gallons of 10% liquid chlorine in the past day or so.

How much chlorine have you been adding daily?

Maybe I missed it, but are you in the middle of a SLAM? If not, your FC should be about 8 ppm.

Thanks,

Jim R.

 

[Lambchop]

Based on advice above, I just ordered a TF100 Refill kit of new chemicals. I have only added about 2-4 cups of chlorine in the last three days.

 

[Sunnydaze]

Based on advice above, I just ordered a TF100 Refill kit of new chemicals. I have only added about 2-4 cups of chlorine in the last three days.

When i moved into my house, an old tf100 kit was left behind where the reagents expired 4 years prior. The fas dpd chlorine test on the old reagent resulted in much, much higher than the actual chlorine level. Definitely an issue with the expired reagent.

 

[Lambchop]

5 years is probably too old for reagents. As Jim mentioned if your chlorine level was that high, the OTO test would have been off the charts. You were reading it at 1 ppm. Have you added several gallons of chlorine lately? You can do a test for FC on your tap water and see what it shows.

I thought I should update the folks who were kind enough to assist me. Your diagnosis of mustang algae was apparently spot on.

Because my CYA was at the upper limit and my water hardness was very high, I proceeded slightly differently as I knew I would have to drain my pool and spa.
Rather than run 12+ gallons of chlorine through the pool for days, I opted to shock the pool using Sodium Hypochlorite, heresy, I know. I first cleaned the pool cartridges and after the sun stopped shining on the pool, I shocked the pool at about 250%. I ran the filters continuously for 36 hours. I then removed the filter cartridges and cleaned them again, started the pump and ran the pool filter. In the evening I added more shock and ran the filters another 24 hours. I needed to speed this along as the heat was increasing and the sun was staying on the pool longer.

I then began to drain the pool. I removed the spa and pool lights and disinfected them and the housings. I completely disassembled my Hayward pool sweep and disinfected it. I soaked the pool vacuum hoses in chlorine and water, cleaned the pool skimmers and baskets, the two pool umbrella inserts (built in to the pool), ditto the hand skimmer and pool brush. When the pool was nearly empty I got in there armed with rubber gloves with several five gallon pails of chlorine and water and brushed/scrubbed every inch of the pool and spa surfaces and I attended to the hard water stains on the tile coping. I washed it down and allowed my submersible pump to drain it into the sewer (required here).

While the pool was refilling, I disassembled the filters yet again, cleaned the cartridges and then soaked them in a chlorine and water mix, just in case. I also used that chlorine mix to clean the inside of the filter housing and added five gallons of chlorine/water mix before reassembling the filter housing.

As the pool filled, I added some chlorine and waited until it was full to add one gallon. Once running, I added CYA via a sock in the skimmer. Of note, per the math calculator, had I followed that formula, I again, would have had a very high CYA reading. The calculator used as a guideline yes, but I recommend adding CYA in small increments and testing. It took far less than was prescribed. I vacuumed the pool and spa several times, just in case, and brushed daily. I tested chlorine, pH, TA, FC, and CYA daily and adjusted until all was reading correctly. (My fresh TF 100 refills finally arrived.)
I am pleased to say I have a crystal clear pool that has no signs of green tinge. In fact, it looks better than it has for a very long time. I guess I really had the nasty mustard algae.
I plan to clean the filters again in 6 weeks, just to make sure they are at optimum clean for summer. I'm finding after seeing the filter cartridge's condition after even 3 months, that I had better reduce the cleaning time to every two months. It does get dusty here. I also find that my pool pump sounds much more relaxed when the filters are clean.

Thanks again to the folks that responded.

 

[mknauss]

Great job in your success!

I opted to shock the pool using Sodium Hypochlorite, heresy, I know.

That is bleach, aka liquid chlorine. Nothing wrong with that.

I'm finding after seeing the filter cartridge's condition after even 3 months, that I had better reduce the cleaning time to every two months.

Clean the filter when the filter pressure rises by 25% over the clean pressure.

 

[Rancho Cost-a-Lotta]

Another success story. Congratulations! Enjoy your summer swim season.