any way to control pH better?

[PoolDoc]

Just saw the photos -- so-called black algae.

And, with an eroded pebble finish like that, you've got a long term maintenance issue.

Could you mail larger versions of those photos to me at poolforum AT gmail DOT com?

I'd like to edit them, comment on them, and repost them here. I can explain a bit more of how and why, and what to do, if you do (BLACKMAIL, here! )

Ben

[dhanger]

PoolDoc-

I just wanted to comment something about the surface, I'm in AZ too, and it seems to be a real popular finish here, the PebbleTec. It's not eroded plaster, as you seem to think (I don't mean to insult your intelligence if you already know what I'm talking about), which is a small pebble inlay with concrete or grout as a binder surrounding it. The difference in depth between the top of the pebbles to the binder is no more than 1/32". I have no idea whether that would affect your diagnosis or not, but I thought it might be helpful to clear that up.

Dan

By the way, I have the same issue regarding pH rising, in my 5 years with this pool, not once have I ever had to raise it, always lowering. Don't know if that has something to do with the water here, the environment, or what.

[PoolDoc]

No insult taken . . . I didn't actually think Pebbletec was eroded plaster, but I've seen pools with, hmmmh, shall we say raggedy edge finishes, so I didn't want to get too specific. The bottom line for me, when I'm posting here, is that I'm usually pretty conscious that I don't really know what the poster actually has on, or in, or around their pool.

In this case, seeing the pictures was really interesting. I hadn't realized that you'd get waterline deterioration of the interstitial filler in Pebbletec like his pictures show.

By the way, do you happen to know the actual chemical or mineral composition of the "pebbles" and of the filler?

PoolDoc

[dhanger]

Well, according to their website-

"Created with pebbles from around the world that are selected for their color and beauty."

So, if they're telling the truth, they are actual pebbles and not some composite. I can't say what the filler is, but it appears to be concrete. Seems I read once how they apply it, a layer of concrete with the pebbles mixed in, then at a point they gently wash off the concrete exposing the pebbles. Can't find that info now, so not sure I have that right.

And, I'm not convinced there is any deterioration going on there. The photos look exactly like mine (minus the black deposits), in fact it looks like there is a calcium ring exactly like mine, that may be what's making it look like deterioration.

Dan

Edit-Actually, the more I think about it, the filler probably wouldn't be concrete as the aggregate would be exposed as well. Guess I have no idea what it is, unless it's just the cement used in concrete, or mortar.

[Furbabyvet]

Ben, I will email the pics to you.

Dan is right in his description of my pool. There is a pretty thick build up of calcium on the pebbles just above the waterline. It is higher in relief than the pebbles below the waterline. Both my neighbors have the same thing on their Pebble Tec pools, so I think this is sort of "normal" for this area. I have a similar build up on the inside of my glass shower door despite having a water softener, but that is an entirely different rant...

EDIT: the algae appears to be green, not black. I doubt this makes much difference in this conversation.
Maybe we will try lowering the water a bit and blasting the algae with 50:50 bleach every time we can and see what happens! Thankfully, it's not around the entire pool. We had this algae worse last year but it seemed to go away, especially when I shocked the tarnation out of it in June (60 ppm-- oopsy) but alas, I guess there were microscopic roots in there.

As an aside, I am using trichlor and liquid chlorine only because I already had the trichlor from last year and I need more CYA in the pool, so I thought I might as well use them up.

Hmmm. I was really thinking the borates were going to help stabilize my pH. Is this hopeless, or should I put some more in? The info here suggests 50 ppm but I stopped short at about 40 just to be cautious.

Tabitha

[CarlD]

I'm not sure why a direct application of bleach to the surface won't at least control it.

[PoolDoc]

Carl, there are a couple of reasons why you might not want to apply bleach directly on a regular basis.

First, simply applying it regularly is a bit of a challenge.

If you pour, you're likely to end up with it on your self. And unless you're doing it naked (but in sun glasses or safety glasses) you're going to tear up clothes. There's something about bleach that just wants to 'reach out and touch' some cotton or Lycra. After working with the stuff for 20+ years, I've thrown out boxes of clothes . . . and I've STILL got holes in just about everything I wear in the summer.

You can get bleach tolerant sprayers. But they're hard to find and in my experience, sometimes not as bleach tolerant as you might think.

Second, if you pour, instead of spraying, you're likely to end up overdosing your pool. Pouring bleach all the way round a pool, I personally would probably end up dumping a gallon or more in the water.

Finally, I'm not sure what it would do the surface. Bleach is a high pH solution, and stuff evaporates RAPIDLY in Arizona, due to the low humidity. Without prior testing, I'd be afraid that some sort of scaling or discoloration might occur on the surfaces wetted directly with bleach.


Using a polyquat mixture in a sprayer is not likely to result in any of these problems.

But . . . from a purely "kill the algae" point of view, putting bleach on it regularly should work fine.

PoolDoc.

[CarlD]

I know we've used bleach in empty Fantastic spray bottles to get at mold and mildew in showers and tubs forever. Even have one now, with "BLEACH" written on it with a Sharpie.

Why not use that? A pint or quart pump sprayer--if it doesn't hold up, you just throw it away. I've ruined my share of pants, shorts and shirts as well! I think if I go near the pool wearing a new Lacoste shirt again my wife WILL murder me!

Plus, you know I'm a BIG fan of Polyquat as one of the two chemicals pool stores sell I appreciate! (the other is CYA, as needed).

[PoolDoc]

If you've got disposable sprayers, and they work long enough -- that would be fine.

I'd still want to dilute the bleach, until I was pretty sure it wasn't going to result in some sort of new and 'special' scaling or discoloration of the surface.

Ben

[PoolDoc]

OK, here's one of Furbyvet's pool pictures with my notes and editing:



Several things to note:

FIRST: Black algae isn't; it's dark green. It appears black when it's thick, or underwater. But if you'll use the 'smear test' -- scrape some with your fingernail, and then smear it on a white card -- it will always appear green to dark green.

SECOND: The scale visible at the top may be calcium carbonate, or it may not. In the Southwest, their drinking water is sometimes so full of minerals that people can 'mine' it! As a result, they can get quite creative with their scales! The easy test is acid: if you flake off a bit, and drop some muriatic acid on it, it will foam or fizz if it is calcium carbonate.

THIRD: Exposed mortar grooves -- between tiles, between pebbles, in cracks and crannies, around light niches or skimmers is algae's refuge. It's always difficult, and sometime impossible, to get enough chlorine or other algicide into those spots to kill off the algae. In this part of the country, I wouldn't even consider a commercial pool management contract on a pool with a surface like that, unless the customer accepted a VERY large algae management surcharge. There's no shortcut to physical cleaning, and you have to do lots of it on a heavily loaded commercial pool with a low quality surface (= equals any surface with LOTS of algae hidey-holes). Very, very expensive glass tile pools, with poor quality grout joints (= rough and/or porous) can be a total nightmare to maintain. Beautiful, but extremely 'high-maintenance'!

FOURTH: What's particularly interesting here is that Furbyvet's algae has found a home at the 'high tide line', where it's wet enough to live (because of the grout joints holding moisture) but low enough in chlorine (because it's outside the circulation system) for the algae to be quite happy.

FIFTH: People, including some pool book writers, often think that black algae or mustard algae or green algae is a species of algae. But, in fact, the names are nothing but a physical description. Black algae is black looking, and surface clinging. Green algae is free floating and not obviously connected to the biofilm layers associated with it. But, in fact, all forms of algae tested by some researchers I've spoken to in the past, were FAMILIES of both bacteria and algae. This is especially true of any biofilms, like the slime that precedes green algae outbreaks, or like black algae. My recollection is that the lowest number of identified species in any single occurrence was over 20, and always included both algae and bacteria.

PoolDoc