Not sure of my problem

[michaelwoosley]

Good morning. Yesterday afternoon I did my pool inspection and noticed something odd on the pool floor. A quick back story... month 1 of our pool season was free of issues. Month 2 AND 3 was spent fighting algae that kinda looks like the stuff I'm seeing now. The start of month 4 was our victory month. The past 30 days (months 4) I was bragging how our pool could have been a model for others to emulate. Everything was fine until the morning after I had super-shocked with our weekly dose of 70% cal-hypo... which we've been using since our SLAM.
A couple things I'm super confused about is the SUDDEN onslaught and the LACK of combined chloramines during testing.
Part of me wants to buy a new filter next year... thinking our 2 year old filter "might be" contributing somewhat to these issues.
The weather here has been pretty much rain, wind free, giving me no reason to suspect algae as the culprit. I'm hoping it's just dirt pumping in from the filter (filter problem of some sorts). What's your thoughts?

 

[ajw22]

Does your pool pass a Overnight Chlorine Loss Test?

 

[JoyfulNoise]

I don’t see a current CYA reading in your logs. The only one in there is from over a month ago and it’s 45ppm. TFP recommends only reporting CYA values to the nearest 10’s and to round up. So 45 should be reported as 50. Please do a CYA test again and try to get an accurate result.

I’m also seeing A LOT swings in FC. Some way up at SLAM level and others where it’s probably way too low. You also are adding chemicals that are unnecessary or ones that TFP does not recommend. For example - it’s almost never necessary to add soda ash especially if your TA is as high as 100ppm. TFP also recommends using muriatic acid, not dry acid, to lower pH. In your situation, vinyl and no SWG, dry acid is not as much of an issue, but MA is still better. Finally, you appear to be adding polyquat-60 algaecide to your pool during a SLAM. PQ-60 reacts with chlorine and causes chlorine demand. It can also act like a clarifying/flocculating agent where it will bind to suspended solids and cause settling.

My suggestion is to post a full set of test results and then follow the SLAM protocol to a T … No. Other. Chemicals.

And to answer your question about CC’s - the presence of algae does not guarantee CCs will be present when chlorinating. CCs form mostly from bather waste (nitrogen/ammonia containing compounds). Dead algae and organic leaf matter does not necessarily cause CCs.

 

[michaelwoosley]

JoyfulNoise, thanks for your feedback. I'll pull another CYA later today. I expect it to be close to 50 or a bit higher since we've been using the pucks.
I'm not sure why you're questioning the FC swings... I do everything manually and when I closed out my SLAM, I purposely threw a few extra random points at FC to help me ensure (psychologically) that I beat the algae... my process. we had quite a few high UV days where 6ppm of FC were eaten and days where only 1ppm was eaten (I'm sure the pucks helped).
I had a high TA and normal pH and was experimenting with the different chemistry to bring down the TA with impacting pH too much...
I haven't added Polyquat60 during a SLAM... the wife just recently purchased that a couple weeks ago after the SLAM. We add 4oz of Polyquat60 as a maintenance chemical 1 day after pool shock.
I'm having difficulty trying to figure out, if this is in fact algae, WHAT has caused it? The weather in my mind has been perfect, no debris blown into the pool... it's baffling.

 

[JoyfulNoise]

I'm not sure why you're questioning the FC swings... I do everything manually …

In your logs there are FC entries in early September that go all the way down to below 2ppm as well as several that show up at 2-3ppm. With a 50ppm CYA, that’s way too low and can allow algae to take hold. What I was trying to point out is that consistency is very important when one chooses to manually chlorinate a pool. A clean and clear pool will lose about 2-4ppm per day of FC and so you should be maintaining a target FC on the high end of the range for CYA plus adding whatever you need each day to put 2-4ppm back into the pool. Most folks that manually chlorinate with simply adjust their FC to about 10% of CYA (let’s call that 5ppm FC in your pool) and then add 3ppm each day with the goal of never dropping below 5ppm. Yes, that means adding a lot of LC every single week in your pool (about 80oz each day or 4-3/8 gallon per week of 10% LC) but that’s how you maintain a manually chlorinated pool. You then test every other day or so to see where the actual FC is at and then adjust additions as-needed to keep your pool running in the right FC zone.

The polyquat really isn’t going to do anything to help and, yes, even a 4oz maintenance dose can eat up some FC. So it’s best to leave that on the shelf until pool closing time.

You might also want to take a serious look at your filter. Backwashing a sand filter doesn’t really clean it all the much. If it hasn’t been opened up in 2 years then you might consider doing a deep clean of the filter sand to ensure that it’s clean and to avoid the possibility that there could be channeling in the sand that is allowing junk to flow through the filter.

You could also try to suction up some of this “algae clump” that you’re seeing (try using a turkey baster) and spread it onto to some paper towel. It might make it more obvious since there are lots of things in the environment that look like algae but aren’t.

 

[michaelwoosley]

In your logs there are FC entries in early September that go all the way down to below 2ppm as well as several that show up at 2-3ppm. With a 50ppm CYA, that’s way too low and can allow algae to take hold.

Yes, I unfortunately allowed the FC to creep where I didn't want it to. I immediately adjusted it back up to 6+ (maybe a little less a couple times near evening tests).

What I was trying to point out is that consistency is very important when one chooses to manually chlorinate a pool. A clean and clear pool will lose about 2-4ppm per day of FC and so you should be maintaining a target FC on the high end of the range for CYA plus adding whatever you need each day to put 2-4ppm back into the pool. Most folks that manually chlorinate with simply adjust their FC to about 10% of CYA (let’s call that 5ppm FC in your pool) and then add 3ppm each day with the goal of never dropping below 5ppm.

I like this approach and will incorporate it into my regime next year. I agree that the bouncing back and forth drastically doesn't likely promote a happy chemistry in my pool.

Yes, that means adding a lot of LC every single week in your pool (about 80oz each day or 4-3/8 gallon per week of 10% LC) but that’s how you maintain a manually chlorinated pool. You then test every other day or so to see where the actual FC is at and then adjust additions as-needed to keep your pool running in the right FC zone.

The polyquat really isn’t going to do anything to help and, yes, even a 4oz maintenance dose can eat up some FC. So it’s best to leave that on the shelf until pool closing time.

You might also want to take a serious look at your filter. Backwashing a sand filter doesn’t really clean it all the much. If it hasn’t been opened up in 2 years then you might consider doing a deep clean of the filter sand to ensure that it’s clean and to avoid the possibility that there could be channeling in the sand that is allowing junk to flow through the filter.

2 months ago we opened up the filter, disposed the old sand and replaced with new. The old sand was probably fine, but the algae problem was SO BAD, we decided to change it out towards the end of our SLAM.

You could also try to suction up some of this “algae clump” that you’re seeing (try using a turkey baster) and spread it onto to some paper towel. It might make it more obvious since there are lots of things in the environment that look like algae but aren’t.

What would I look for if I was able to capture a sample of one of the globs? I'm assuming if it's slimy it's algae...

Thanks again for your assistance with helping me out.

 

[michaelwoosley]

Does your pool pass a Overnight Chlorine Loss Test?

I haven't tried that yet, but will tonight.

 

[michaelwoosley]

Does your pool pass a Overnight Chlorine Loss Test?

I have not tried that yet ... will try tonight

 

[JoyfulNoise]

What would I look for if I was able to capture a sample of one of the globs? I'm assuming if it's slimy it's algae.

Most pools develop blue/green type algae. It looks dark green and when you smear it on white paper it leaves a green streak.

I once found a gooey tan clump of gelatinous black seed-like snot in my pool. Collected it and smeared it out but it just looked like tiny little kiwi fruit seeds in a gelatinous goo. After some searching I realized that it was just frog eggs. We have Sonoran brown toads here (the ones with the psychedelic slimy skin that can make dogs very sick). They like to lay their egg caches in swimming pools.

 

[sande005]

If not very much, it may be a side effect of the Polyquat acting like a floc/clarifier - and dropping other suspended stuff to the bottom. Vac it to waste, and see what does/does not return....

 

[michaelwoosley]

If not very much, it may be a side effect of the Polyquat acting like a floc/clarifier - and dropping other suspended stuff to the bottom. Vac it to waste, and see what does/does not return....

it was quite a bit... let's say 30-40 spots