BBB doesn't always work

[chem geek]

Well, dead algae was alive at some point so we still need to get this figured out, but you're on the right track.

 

[tcat]

My "guess" is when I switched to the 2 speed motor, I was doing a lot of "tweaking" with my Clorox feed. And I was aiming to closer to low end of recommended FC, so at some point FC could have hit 2 or 3. It couldn't have been long, but with 100 degree weather, I'm sure it doesn't take long to get something growing! Going to aim at "5" and up from now on.

edit: Dang, I though an auto "flow" of 1-2 quarts would be adequate while at work... came home it's at 13.5. I guess FC comes down a lot faster than 2ppm per day from shock level. Back at 17 now, will check in an hour.

 

[tcat]

OK, this thread should probably be moved to the algae section... but "discovery":

I am close to meeting the overnight OCLT, but did get a -1.5, so continuing slam today. Before I started today I decided to clean my DE filter... what a surprise! Thickly coated green "gunk" (definitely green). I can't imagine algae growing with FC at 17 and in the dark of a filter... dead algae? The strainer thing on the tube at top was caked with about 1" of sludge (nothing getting through it). Still working on cleaning the filters, one question:

I switched to cellulose (Zeofiber) about 6 months ago, works well, but wondering if it's more susceptible to algae than DE. Went I added it I only did a thorough backwash (3 times), but never took apart the filter; probably big mistake. Now that I will have it clean, does it matter which I use? Also, can I spray the filters with something like Clorox2?

edit: sprayed with Clorox, rinsed off after 10 minutes. Reassembled. With "filter" (no media), High went from 28 to 18, low went from 7 to 4. I don't normally wait for pressure that high, but I it was 24 before I replaced my jets with slotted ones, pressure went to 28 after that so I assumed it was the jet restriction. Wrong...

OK, I have one more load of Zeofiber... or off to Leslies for a bag of DE...??

edit2: Interesting, my FC went from 17 to 18 (then I noticed I had my chlorine feed on - only 16 oz. had gone in in an hour, turned it off)... then an hour later it's now 20! I'm think water is getting circulated much better and "hot spots" got dispersed. I checked my tank and no Clorox had entered in the last hour... will check again in an hour. I think the algae in my filter was the problem!

 

[chem geek]

It sounds like the algae in the filter was a continually feeding source of clumped algae, but that the formation on the walls may have been due to poor circulation, partly from the slower flow. If the green gunk bleaches out if you add bleach to it, then that indicates that for whatever reason it wasn't getting great water flow into that area of the filter (or that the algae has gotten to the point that it has developed a chlorine-resistant slime layer -- usually that is for black algae and for bacterial biofilm, not for green algae). At some point, though, if there is enough growth the algae will grow faster than chlorine can kill it (at normal FC levels) and the chlorine just gets consumed at the surface layers of the algae clumps and isn't enough to penetrate more deeply to kill it off. That's one reason why shock FC levels are significantly elevated.

The "minimum FC" is called that for a reason. It's the minimum when everything is done right including good circulation and flow in the pool and in the filter. It also applies to green and black algae, but yellow/mustard algae requires a higher (roughly double) FC level which is why we usually recommend complete eradication for that algae which likes to hide in shady places such as behind light niches and under removable ladders. Fortunately, it sounds like you have green algae that is easier to deal with.

 

[tcat]

Now that my filter is clean, my low flow appears about twice as fast (high is like 4 fire hoses!). I think low at 12 hours will be good circulation. Yes, the algae problem had to be in the filter (me not manually cleaning it when I switched to Zeofiber, and me likely missing a minimum one day). Now my problem is I used so much 0870 and 0871 I'm down to 1 or 2 tests (maybe half tests). Ordered from TFTK and has shipped, hopefully here by Thursday. Going to test when it gets dark and when I get up and hope I meet OCLT. Happy holding at 16-17 all day (105 degrees) adding only 2 quarts of bleach.

Edit: I used 5ml samples, 8pm-20 drops, 6am-20 drops! Cc almost zero, clear pool! Not sure how fc got to 20, since at 6pm it was 17, not going to worry about it until my new chemicals get here.

 

[chem geek]

One thing that bothers me is that algae may get caught in the filter, but shouldn't grow there because there shouldn't be any light in the filter. Bacterial biofilms can grow in filters, especially in high bather-load commercial/public pools where they often use rapid-rate horizontal filters that can form dead spots, but every now and then we see one in a residential pool with clumping, especially if the chlorine level got low for a time. Living algae, however, isn't usually seen in a filter (of course, when first filtering an algae bloom, it will look alive -- I'm talking about something growing in the filter rather than being caught there).

 

[tcat]

All is going well (BBB really does work!). Got my FC chemicals and was able to do reliable tests starting yesterday. Pool stayed at 10 overnight. Dropped only to 8.5 after 12 hours (just now), which is great considering it's 100+ with 86+ water (and no chlorinator running). Pool is crystal clear. Aquabot 4WD picked up some "dust", but even it was fairly clean. Low speed has plenty of flow to keep Poolskim sucking and even main skimmer is pulling, surface is spotless. Got to say that jet direction makes a huge skimming difference. I had all aimed clockwise and seemed a lot would end up staying in the center; I reversed the direction yesterday and everything gets sucked up (must be a hemisphere thing). Plan to get my borates back up to 50 from 30 in the next day or two.

Not sure if the filter algae was dead or alive, just a green sheen on every surface, and clumps of old DE; probably what it was picking up from the pool since it can't grow in the dark (no windows on my filter!). I think the Zeofiber will clean much easier.

 

[terryc]

So my pool gets a lot of leaves and and often even frogs and stuff. I think this will cause FC drop so it will be hard to follow the slam process. I guess I'll have to wait until I get a good tester to see.

 

[chem geek]

Leaves don't create too much chlorine demand unless you are talking boatloads of them -- it's partly due to surface area which isn't large compared to microorganisms like algae and partly due to their relative robustness. They do eventually fall apart from the chlorine though large parts remain intact (the cellulose, for example). Frogs, well, that's another matter -- depends on their bathroom manners.

 

[terryc]

Leaves don't create too much chlorine demand unless you are talking boatloads of them. Frogs, well, that's another matter -- depends on their bathroom manners.

The leaves aren't to bad now but earlier in the year we had a ridiculous amount of little cauliflower like blooms off of our bodarc tree. Also when I clean out the pool cleaner we have a lot of Rollie pollies and caterpillars.