I hate mustard algae

[topless]

I'm so pleased to find some help with my pool. I've about given up trying all the various products from the pool stores.

Anyway, my pool is inground, 15,000 gallons. I have used a 3" tablet chlorinator since I bought the house with the pool. I took a water sample in for testing, yesterday after using a quart of Leslies copper algae control. I shocked it then circulated for 2 hours and let it sit for 36 hours before back flushing, vaccuming to waste. I was so disappointed to find the mustard algae returned overnight. It's about as bad as before I vaccumed it out.

Here are the testing results:
FC - 10+
TAC -10+
ph - 7.2
TA - 260
Calcium Hardness 500
CYA 150

They told me to add a 1/2 gal of muratic acid and test again. I added it this morning, so tomorrow I was going to take a sample in again.

I was pretty clear of algae until about 3 weeks ago when we got a midnight rain, I have a power cover, and usually close it to keep the rainwater out.

Until my test kit gets here, I have a test kit that I bought from one of the pool stores.

[b2001]

My pool has been Baquacil based summers previous to this one; my past problems have been more with white mold rather than mustard algae. However, I converted to chlorine this year and got lazy with chemical maintenance recently, and have had what appear to be mustard algae problems like what you describe. I would vacuum it and it would be as bad one or two days later.

My solution was to keep the pool at chlorine shock level for about three days and after that, making sure that my chlorine stays at an acceptable level based on my cya. Initially, I shocked it for one day, and the problems came back, so a few days later, I went through the second and longer "shock" process. I haven't had the algae problem now for about two weeks. I plan on shocking about once every two weeks for preventative measures. I'm using bleach from the store.

Also, I used a bottle of polyquat algaecide - I'm not using the copper based algaecide, there have been discussions against using it on this forum, if I recall correctly. Do a search on polyquat on this forum for specifics. Lowe's, Home Depot, and Tom Thumb supermarkets carry it in the Dallas area.

Read these articles, if you have not:

http://www.poolforum.com/pf2/showthread.php?t=365
http://www.poolforum.com/pf2/showthread.php?t=1113

and read as many posts as you can. If you don't already know, one thing you will find out if you keep reading, is that your cya is high and the tablets will keep adding to it. I'm having a different problem, I don't use tablets - bleach only - my cya is constant and low, so my chlorine levels go down during the day, hence the problems that I'm having if I slip up on chemical maintenance.

According to the best guess cya chart in the first link above, an FC of 10 is acceptable for your pool based on your cya level - but you would need to bring the FC to 25 for it to be at shock level.

Usually, I pour a bottle or two of bleach in my pool if I know its going to rain and my chlorine levels are on the low end of where they should be, and I haven't had any problems with rain.

Hope this helps for starters ....

[topless]

This was the only time I used the copper based algaecide, and my last. I've been using some that I bought from Sam's Club that the main ingrediant is diemethyl benzol chloride (I read it, but doubt if I spelled to correct). Prior to that was the Bioguard algaecide and Banish. I'm not satisfied with any of the products since I can't keep the algae out of my pool.
According to the bleach calculator, I should add 2-1/2 gallons to raise my FC over 20ppm.

[KurtV]

topless,

According to the Best Guess table, for your level of CYA (150 ppm according to your first post) you need to get the chlorine to 25 ppm to shock. You'll need to keep it at that level until the algae is gone and the water will keep the same level of free chlorine overnight.

Testing several times a day and adding bleach to return the chlorine to shock level will give you the best results. At a minimum, test and chlorinate in the morning and evening but three times a day will probably get this problem cleared up more quickly.

Best of luck.

[topless]

Thanks for the help. Unfortunately my start is delayed by rain today. I've got 8 gallons of bleach and my Bioguard test kit all ready to go, but I closed the cover to keep the rainwater out. It's supposed to stop by tomorrow.

[Simmons99]

Also you need to brush the pool daily.