having possible mustard algae problem 3 weeks now

[bluebayou]

I have an older inground pool with vinyl liner. I have growth that starts as a yellow-brown dust and then spread to to have green under the original dusty spots. The growth is only on the horizontal or sloped surfaces of the pool, not on the sides, and it is in shade or sun.

I went to 20 ppm FC (by estimate) with 11 bags of cal hypo shock. The chlorine level was to 3 the next day and zero the day after. I realized that I had no CYA.

I have added 6 pounds of CYA to try to get to 30 or so (yellowish brown on test strip, not quite brown). I brushed the pool. I added shock to get to 12 ppm and it held above 10 on the test strips for three days. Today it is around 5. The pool has stayed green and cloudy since brushing and now I have growth on the pool floor again.

I am unsure what to do because:
Historically, I have used cal hypo tablets and shock. Last summer I used trichlor tabs and apparently got my CYA out of whack.

Last September I had a pipe break and I didn't try to recover the pool for 5-6 weeks. The pool had very bad green algae. I shocked and shocked, maybe 30 pounds. I realized that my CYA was over 100.

I drained the pool partway and added 15 thousand gallons. I have shocked the pool occasionally over the winter, but had no real problems with the lower temperatures I am guessing.

Basically, I THINK that I need to raise the CYA a little more. I am hesitant to add stabilizer, but am planning on adding more slowly. I THINK that I need to add shock to get up to 20 ppm and maintain it for a few days.

If someone could tell me what to do or tell me what other info you need, I would appreciate it.

[PoolDoc]

1. Go buy a cheap OTO/phenol red drops kit. Use it to maintain your chlorine level in the DARK yellow to orange range.

2. Tell us your pool dimensions, so we can figure doses.

3. Order a K2006 kit, so we can get accurate test results => http://pool9.net/tk/
Before you use it, watch the videos:

http://pool9.net/tk-guide/
http://pool9.net/tk-interfere/

We call test strips 'guess-strips' for a reason, and the CYA measurements are especially inaccurate.

4. Low phosphate levels aren't essential for algae control, but WILL enable you to eradicate it more quickly, and more easily avoid it in the future. BUT, it will probably cost you $100 more, and will require another kit and monitoring another factor. If the money doesn't bother you, get the Taylor phosphate kit when you order the K2006. 4 quarts of the Kem-Tek product should be enough for most IG pools at typical phosphate levels:
Kem-Tek 265-6 Pool and Spa Phosphate Remover, 1 Quart
But, be sure you understand: CHLORINE kills the algae; low phosphates just makes it easier to kill.

5. Read the Cl-CYA page -- it's essential for you to understand that your correct chlorine level is determined by your CYA level:
http://pool9.net/cl-cya/

Good luck!

[bluebayou]

Money is a real problem right now. That is most of my frustration because I spent $100-150 in the last week. I just changed jobs and everything is a mess.

the pool is a vinyl lined 20x40 with roughly 30,000 gallons.

I can't afford the phosphate test and chemicals right now, but I think that a proper test kit would be a good investment.

Unless you say otherwise, then I am thinking shock to 24 and adding more stabilizer to get to 30-50, brown guess, on the test strip over the next few days. Thinking that I will add 3-4 more pounds of stabilizer to see what I read on Thursday


I will reread the Best Guess information.

so, you think that I am going in the right direction?

I have a drop kit right now and it is a strong yellow for the chlorine side.

[PoolDoc]

OK, if you're strapped let's look for alternatives.

In most cases, the cheapest source of chlorine is Sams trichlor -- IF that's available to you. Can you get Sams 40# bucket of trichlor?

If you can, I think I can work out a method using OTO testing and treatment with just bleach, borax and trichlor . . . plus brushing a lot.

[bluebayou]

any advice would be great. Before reading your last reply I shocked with 10 pounds of cal hypo yesterday.

This morning I have visible powdery algae on all horizontal and sloped surfaces. The test strip turned dark purple immediately going into the water. I have never seen such a saturated purple color before. I am pretty sure the chlorine is high.

could this just be pollen and I am flipping out for no reason?

I vacuumed the accumulations of algae. Then I brushed all of the flat surfaces. I am going to brush the sides later this afternoon.

What about turning off the pump to let everything settle and then vacuuming tomorrow morning?

my most immediate problem is that I need results quick because I am going out of town on Saturday and will be gone for 2 weeks. the rest of the family can follow simple instructions, but anything complicated......

[bluebayou]

the last picture is what it looks like when I brush

[PoolDoc]

I'd recommend vacuuming up what's already on the bottom, first. Do this:

1. Your chart says you have a 2 speed pump. Put the pump on LOW speed, and run it 24/7.
2. Make sure the chlorine is STILL very high, and then brush the pool completely, to expose all the algae to chlorine.
3. Check the chlorine an hour later to make sure it's remaining high.
4. Wait 24 hours, and then vacuum up the algae. Stay on low speed. Put a towel over the main drain to block it, if you don't have a valve.
5. Continue to keep the chlorine high. Brush the pool again, if algae remains on any surfaces.
6. Let me know how it goes.


Watch the pool returns -- make sure algae is NOT going through the filter and returning to the pool. If it does, you'll need to get some DE filter powder from Lowes or Home Depot.

[bluebayou]

Yesterday I did as you suggested plus added 24oz of HTH Algae Guard. I rarely use the algae guard, but I am frustrated.

I vacuumed, then checked FC later in day (it was still high), brushed the entire pool (I DID find some green growth on vertical wall in shallow end which is shaded), and then brushed again about 7pm.

The water started to clear about mid afternoon yesterday. This morning it was crystal clear, but I didn't look at the bottom. Today, at 6pm, the water is still crystal clear with fine gray powder (presumably dead algae). BUT, I have the same yellow brown dust in a very thin layer in the shallow end.

I brushed it again. The test strip is still deep purple for FC. I was debating adding more cal hypo shock

its funny that you mention the DE. I was wondering the same thing. the steps into the pool accumulate dust, sand, and the algae. It looks to be blown from the returns mounted in the steps. I don't notice anything around the other returns, but water is a low deeper.

Please tell me that I can add that to the skimmer and not have to crack the filter ope

[PoolDoc]

Yesterday I did as you suggested plus added 24oz of HTH Algae Guard.

I suggested algae guard???? Where did I do that? Algae guard is cheap (well, maybe not, but it should be) foamy algaecide that's not really effective against anything. If I suggested that -- and I'm not seeing it in my posts -- I was having a 'senior moment'!

The purpose of adding DE is first of all, to see if your filter is working properly. If you add DE, and it blows out into the pool, that is pretty much proof that you do, indeed, 'have to crack the filter open' -- an unfortunately painful task on top valve filters.

[bluebayou]

no, you did not suggest the algae guard. I was frustrated and added it. I followed the steps that you suggested, but I ALSO added algae guard.