Re-occurring ZOMBIE Algae...

[PoolDoc]

I am tempted to get some powdered shock and see if that will help?

You need to stop thinking of pool chemicals by their brands or descriptions, and start thinking of them by the chemical they contain. "Powdered shock" could be an excellent choice OR a terrible one, depending on which CHEMICAL is present in the "powdered shock" you have in mind. Neither we, nor you, know whether that product is good or bad for your pool, till we know what's actually in it.

Pool store operators and especially, pool chemical makers, really, really want to prevent you from getting involved "in the complications of pool chemicals and their effects": they want you to let them "make it easy for you". And honestly, if they actually did just that, PoolForum would be unnecessary. The problem is, they don't. The reasons are complex and pool store operators are themselves somewhat the victims of misinformation and misdirection from the pool chemical makers. But the bottom line is, the primary purpose of pool brands is to (a) sell you cheap chemicals expensively and (b) sell you rarely needed but high margin chemicals routinely.

Back to your pool: dusty debris on the bottom could be any of the following: mustard algae, dead algae (either green or mustard), sand from your filter, blown in or tracked in dirt or pollen.

You can probably rule some of these in or out yourself:
+ No dusty wind? Then, no blown-in dirt.
+ No pollen on flat surfaces outside? Then, no bulk pollen in pool.
+ No body tracking in dirt or sand? Then, no tracked-in dirt.
+ No yellowish-green somewhat uniform coating on your pool walls and floor, prior to accumulations of powder? Then, the dust is is not dead mustard algae.
+ Dirt does not feel gritty between your fingers, when you pinch a bit of it up? Then it's not sand.

[Waldog]

Is there a recommended dry shock? Just curious. I would never visit the pool store for chems BTW. I would use Walmart because at least there I won't be bothered by pesky pool store sales people. LOL Sorry, I didn't mean to make you fret. I'm just frustrated. I will most likely pickup MORE walmart bleach since it does seem to be more potent than the Aldi bleach I was previously using and bring the pool up to SHOCK level... again...

To answer your questions:
You can probably rule some of these in or out yourself:
+ No dusty wind? Then, no blown-in dirt.
Well, it's been windy, but during our torrential downpours.

+ No pollen on flat surfaces outside? Then, no bulk pollen in pool.
Noticeable pollen was early this spring. I have not noticed it on vehicles or other surfaces around my house. However, we have 2 acres and lots of trees. It could be wash off the trees, no?

+ No body tracking in dirt or sand? Then, no tracked-in dirt.
No one has been in the pool since Saturday night, and I had vacuumed the pool Sunday.

+ No yellowish-green somewhat uniform coating on your pool walls and floor, prior to accumulations of powder?
Then, the dust is is not dead mustard algae. - Well on the floor near the seams where the floor meets the walls.

+ Dirt does not feel gritty between your fingers, when you pinch a bit of it up? Then it's not sand
Pool is too deep for me to try that, can't lean over and grab some, but it is NOT disturbed by my skimmer pole, but is brushed away with the pool brush.

[PoolDoc]

Pool is too deep for me to try that, can't lean over and grab some, but it is NOT disturbed by my skimmer pole, but is brushed away with the pool brush.

Sounds like sand. Can someone swim down and check it?

[Waldog]

Sounds like sand. Can someone swim down and check it?

Well, I brushed this morning and it turned to a green cloud... but... what you say makes sense, and I say this because I recently changed where my return was facing. They recommend you face it to make the flow of water go clockwise assuming the skimmer is 6'oclock, but I found if I kept it this way, skimming was reduced. So I've had it facing down... which would cause anything coming back in, sand or otherwise... to be spread out to the edges of the pool floor. Make sense?

I'll check when I get home, and try to inspect the suspect more closely. LOL

Thanks for all your help!!!

[PoolDoc]

Woah! Stop the train!

If you brushed it, and got a green cloud, it's mustard algae. End of story! (You could ALSO have sand present.)

[Waldog]

Woah! Stop the train!

If you brushed it, and got a green cloud, it's mustard algae. End of story! (You could ALSO have sand present.)

Yeah... that's what I've been saying all along. I suspected Mustard Algae... Sand I'm not so worried about. My yard is a sand pit for the most part.

So what can I do to defeat the mustard algae... you have mentioned high phosphates as a contributor to pools that experience mustard algae.

Can I get some phosphate reducer and give it a shot, and bring my shock level to mustard level and maintain it?

Is there a magic potion I can use? Some sort of algae dance? Just keep my FC high and keep brushing and pray it eventually goes away?

A small strategically placed nuclear device maybe?

[PoolDoc]

I'll help you get some phosphate remover. I'm currently using it, and it seems to work well, BUT . . .

You have to understand it's something an unrelenting process, that requires you to CONTINUOUSLY maintain a low PO4 level (< 0.125 ppm). Typically this will mean adding a small amount of PO4 remover every time you add water. It may require that you add a bit of clarifier to clear the resulting cloudiness.

You MUST understand that adding PO4 remover does NOTHING useful until you reach that 0.125 ppm threshold. If you reduce your PO4 level from 3 ppm (3,000 ppb) to 500 ppb . . . it may not help at all!

I'm trying to work this out on a 200,000 gal country club pool now. It loses about 1" of water per day, and is refilled with city water with 2 - 4 ppm PO4 levels (2,000 - 4,000 ppb), so it's necessary to add a small amount of PO4 remover at least every other day.

You'll also have to look at what chemicals you are using, and make sure you are not using anything that adds phosphates. If you have a problem with metal stains, this can be a challenge, since the effective metal chelants are based on phosphonates, and eventually release 'ortho-phosphates' (the algae-feeding kind). However, quite a few pool chemicals contain 'stealth phosphates', such as almost any product made by United Chemical (unless they've recently reformulated).

This REQUIRES that you use an accurate phosphate kit.

If you're up for this, I'd be happy to help. From what I can tell, it's pretty easy and not very expensive . . . once you work out a maintenance program for YOUR pool. In fact, I hope you do pursue this, since I'm looking for others who can test the process.

But, I'd be unfair to you if I didn't suggest a possible simpler alternative: draining and refilling! I do NOT know why some pools are prone to mustard algae. And in my local experience, draining and refilling does NOT solve the problem. But, it might for you, and then you wouldn't have to mess with one more factor (phosphate levels).

Lemme know what you want to do. Because of the kit cost, getting started with PO4 removal will cost you about $80. However, with a 5k gallon pool, you should be set not only for this year, but next season as well.