having possible mustard algae problem 3 weeks now

[PoolDoc]

+ Do NOT open your filter. Do NOT backwash your filter UNLESS there has been a 3 - 5 psi pressure increase.

+ DO get some DE and test your filter immediately!

+ DO get an HTH 6way kit IMMEDIATELY. If you cannot get one, get a local OTO / phenol red it. We *NEED* to be able to test your chlorine at levels above 10 ppm. http://pool9.net/tk-hth6/

+ If you cannot get a 6way, but have to get just an OTO, ORDER a K2006. We *NEED* to know what your CYA level is

+ STOP ignoring our instructions OR I will close this thread. There are other people who we *can* help, because they *are* listening.

[bluebayou]

I am sorry if I offended you. I made a mistake adding the algaecide and I accept that. Otherwise, I just considered my posts as "thinking out loud".

No one has a 6 way kit locally. I have a OTO/Phenol kit and the reading today is shown below.

I do not understand whether you prefer the HTH 6way over the K2006. I will have to order one either way. I will order what you recommend.

[Watermom]

Definitely prefer the K2006! Can order it through this link: http://pool9.net/tk/

Another link that may be helpful shows shows you how to interpret OTO readings that are off the scale: http://pool9.net/oto-chart/

[bluebayou]

I got the DE and added one cup mixed with pool water into a skimmer. There was not a visible result from any of the returns.

The FC is at 5 according to the OTO kit.

The k2006 kit is scheduled to arrive on Monday.

Today the pool has a very fine film of rust colored dust around the returns (maybe 3-4 feet around). Otherwise, the pool floor is starting to accumulate the powdery looking algae. It always starts accumulating wherever there are wrinkles in the liner or at the angles where the inclines meet.

[PoolDoc]

OK.

We won't know for sure till you have the K2006, but your pool is acting like you have (a) a very chlorine resistant strain of algae and (b) high levels of stabilizer. Watch the guide videos, especially the one on CYA testing so you'll be able to get a good reading right away.

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

The only preference I had for the 6-way was for finding our your CYA level sooner rather than later.

I scanned back through the thread. Without using phosphates, the only other option you have for mustard algae is higher chlorine. I'd recommend dosing till the OTO has an orange tint. As you push levels higher, the risk of liner bleaching increases. But you really don't have any other options.

You *could* use high levels of copper, but the amounts you'd need (unless you used plain copper sulphate) will cost more than treating for phosphates, and will likely stain the heck out of your pool.

Foamy algaecides don't work against mustard, and polyquat is not much better.

You could use the ammonia based products, to generate monochloramine, but your pool water will become very irritating to eyes and skin. And the clean-up is a mess.

Borates may help somewhat preventatively, but I haven't seen any evidence that they will help once the algae is established. And again, establishing an effective 60 ppm borate level would cost more than lowering phosphates.

Just in case you run into them -- there are some anti-mustard algae products that contain sodium bromide. Do NOT try these; they turn your pool into an unstabilized bromine pool for an unknown period of time. Using them will cause your chlorine use to skyrocket and will accomplish nothing you can't already accomplish by raising chlorine levels directly.

[bluebayou]

ugh. I drained down the pool last fall because the test strips were showing over 100 ppm on CYA. It was expensive to refill, but I have to fix this.

The test kit should be here Monday. I am going out of town, but my wife is going to test it. I will post the results ASAP.

(I will not add anything else to the pool till I hear from you)

[PoolDoc]

You probably missed this, buried under all my other verbiage:

I'd recommend dosing till the OTO has an orange tint. As you push levels higher, the risk of liner bleaching increases. But you really don't have any other options.