When I shock....I get this

[Tony56]

22,500 gal Vinyl liner pool...chlorinator off

Used Calcium Hypochlorite instead of tabs..

I have been having a time with the stuff in these pics...

I assume it is mustard algae....

I don't really know...

It is not yellow...more or less grey....

When I brush it...it turns into a cloud and dissapears...

A little gets on my steps...you cannot feel it..

I have been fighting it since May...and already spent over $500.00 on it...

It keeps coming back...no matter what I do...

I've done what my local pool store suggested...

I believe...originally the problem was due to a very high CYA...over 100...(chlorinator on too high)

Bromine...Black magic...Pro Team plus...

Put all the toys, brush, hose, etc...in the pool while treating..

After 4 days...I thought it was fixed....cleared up good..

I was told not to turn the chlorinator on...

But needed to shock it with with 4lbs of dissolved non stabilized granular chlorine...

Calcium Hypochlorite....

The attached pictures show what happened


I went to Leslie's...

Did their routine...

Got the PH to 8.0...then Yellow out..then 12lbs Power Powder Plus in about 30hrs...

Thought it cleared up....

After a couple days...I decided to add more Calcium Hypochlorite.

Still having problems....

After starting any of the treatments....

I have always gotten the water numbers where they were supposed to be...(CYA being in about 65-70)

Over a week...I have basically drained the whole pool now...and refilled it a foot at a time...

The CYA is now at 40...

So I turned the chlorinator on to .5

I have read and read and read...I do understand a lot more now..

It seems to have slowed somewhat...but I still get it...

My chlorine is .5....the PH is 7.4...Alk....100

I am hesitant to turn the chlorinator higher than .5...for fear of raising the CYA.

It seems that every time I shock the pool...the algae or whatever it is EXPLODES...

Can anyone offer an explanation to what my problem is...or what is in the pics...???

Thanks....

Tony

[chem geek]

Does it mostly grow on the shady side of the pool or does it mostly settle in the same place every time away from the returns? It might be yellow/mustard algae (which prefers shade) or it could be dirt or pollen. If it's dirt, check your filter; if it's pollen, use a skimmer sock; if it's really yellow/mustard algae then the Yellow Out treatments should have killed it, but it may have been reintroduced. In any event, shocking shouldn't bring back the algae (I assume it's not just undissolved Cal-Hypo -- once you stir things up, it should mostly dissolve unless it's poor quality with lots of fillers that don't dissolve).

[Tony56]

Thanks Chem Geek....

The stuff does not prefer the shade...

Actually...I have more of it in the sunny deep end than anywhere else....

Not much will be visible in the mornings.....

It seems to prefer the sun.....

The pool is oriented to get just about full sun the whole day...

I don't have hardly any shade at all...until late in the evening..

Then only about 30 minutes...

It most always settles on the seams of the liner in the shallow end...

It settles on the return side as much as the opposite side...

I had just a touch of it at the end of the season last year....

Tried the Bromine...Black magic...but didn't get rid of it all...

I also changed the sand before I opened it in May....

The last few days...I have just been brushing it because it is not as much as in the pictures...

But I know it is still there...

The guy from Leslies told me the granular chlorine could be making it bloom...and it is trying to stay alive

Anyway...it is definitely less since I turned the chlorinator back on....

But I want to raise the chlorine level some...

How should I do that...without raising the CYA too much..???

Thanks again...

Tony

[chem geek]

Read Defeating Algae and use chlorinating liquid or bleach to raise the Free Chlorine (FC) level without increasing either Cyanuric Acid (CYA) nor Calcium Hardness (CH). Be sure to pour slowly over a return flow with the pump running at the deep end. You can also lightly brush the side and bottom after you pour any concentrated chemical into the pool.

Please get yourself a good test kit, either the Taylor K-2006 you can get at a good online price here or the TF100 from tftestkits.net here with the latter kit having 36% more volume of reagents so is less expensive per test. Pool stores are notorious for giving inaccurate measurements, especially for the CYA test.

[awright221]

Have you tried FLOC... Use 1 Bottle of Floc letter filter run long enough to mix into water then turn filter off and leave off ..... After 24 hours vacum pool on backwash. You may loose some water but gaurantee it will be cheaper than what you are spending on chemicals. I had this problem I would vacum and my water would get cloudy I shocked over and over and used several things then finally 13 dollars made everything better after months of fighting with this problem.

[AlanGMyerson]

(I assume it's not just undissolved Cal-Hypo -- once you stir things up, it should mostly dissolve unless it's poor quality with lots of fillers that don't dissolve).

That's exactly what it is, poor quality calcium hypochlorite with lots of fillers that don't dissolve. Stop using calcium hypochlorite. Use liquid chlorine instead.

[litoralis]

:wave: Have you tried FLOC... Use 1 Bottle of Floc letter filter run long enough to mix into water then turn filter off and leave off ..... After 24 hours vacum pool on backwash. You may loose some water but gaurantee it will be cheaper than what you are spending on chemicals. I had this problem I would vacum and my water would get cloudy I shocked over and over and used several things then finally 13 dollars made everything better after months of fighting with this problem.

Don't ever vacuum the pool on backwash. All the junk you pick up goes into the bottom of your filter, and is dumped right back, when you resume regular filter operation. Always vacuum to waste.