fighting mustard

[izzysmommy]

My mother in law had a pool company let her pool get infested with mustard algae as a result they were fired and I am now the one appointed to taking care of the pool I have never taken care of a pool before so I'm clueless. we brought a sample of water to a pool supply store and there was no chlorine and we had to add acid as well then a lot of algaeside (sp?) It's been over a month of adding and scrubbing it has gotten better but there is still lingering algae that refuses to leave I am hoping some experienced pool keepers can help me maybe give some advice to speed this up thanks

[aylad]

Hi, and welcome to the forum!

In order to fight a bad case of mustard algae, you're going to need to be able to test your water yourself instead of relying on the pool store for testing. We highly recommend the K-2006 test kit in the link in my sig (you will have to log out to the main forum page and then the testkit link will be in the sig of any post made by me, Watermom, or Pooldoc). We need a set of test results taken with a drop-based kit, as well as a list of what chems you've put into the pool so far ingredient names, not product names like "algaecide".). We also need to know your primary source of chlorination, and the size/type of your pump and filter setup.

If you can supply us with that info, we'll be glad to help! BTW, while you're logged out and following links from our sigs, click the google search link and search for mustard algae--it should return a wealth of other threads from the forum and archives for you to read so you'll have an idea what you're up against.

[izzysmommy]

I will be sure to pick a test kit up tomorrow. I will list the levels I just got when we had the water tested Tuesday. Free chlorine is 3.0 ppm,ph was 7.6,alkalinity was 80 ppm, calcium hardness is 325 ppm, stabilizer was 100ppm, and total dissolved solids are 1600 ppm. The pool is 35,000 gal not sure of the brand of filter is a sand filter on a timer. We backwashed it to get it down to 20 psi from almost 40 we use the suncoast gold liquid chlorine as well and the chlorine tablets in the floater. For the algaeside we are using the suncoast stop yellow. Sorry I'm new to all of this and appreciate all the help I can get. Anything else you need to know I will do my best to find out.

[aylad]

In order to fight mustard algae, you're going to need a kit that will accurately test high levels of chlorine. That's why we recommend the K-2006 above. At the very least, the K-1515 is the chlorine part of the kit and will work, as well. With a stabilizer level of 100 ppm, you're going to need to shock your pool to 25 ppm of chlorine and hold it there by testing and adding more chlorine as often as possible. Those with very reisistant mustard algae sometimes find that they have to go even higher than that, which is why you need a kit that will test chlorine levels that high. If you can't follow the link to the "best guess chlorine chart" in my sig above, then log out to the main forum, go to "chlorine and chlorinating chemicals" subforum, and click on the sticky for the best guess chlorine chart. It will show you that as your stabilizer levels rise, so must your chlorine levels in order to not end up in the situation you're in. Sounds like your pool service just didn't keep the chlorine levels high enough. A pool with a CYA level of 100 should never have a chlorine level less than 8 ppm.... Be that as it may....

Since your stabilizer is already very high, you really need to stop using stabilized chlorine, which is probably what is in your floater. Check the ingredient list, and if you see trichloro......(long name), then that's trichlor, which is adding stabilizer as it adds chlorine to your pool. I don't know what's in the suncoast stop yellow, but if it's ammonia based, it's also creating a very big chlorine demand. I would stop using any of that, shock the pool, brush it daily, and see if it won't speed up your cleanup.

Do you know what the HP of your motor is, and the capacity of your sand filter? If you can still read the numbers on the label, they should be listed there...

[izzysmommy]

Just checked and the chlorine tablets do have the trich in them so ill hold off on those I'm not sure of the stop yellow as we threw out the canister the filter is a hayward pro series 220t its raining right now but when it stops ill go see if I can read them off the unit itself. My mother in law does have the aqua chem test kit but it only goes up to 5.0 on the chlorine. Sorry for sounding like an idiot I've just never messed with any of this before

[izzysmommy]

The motor is 2 HP. On the filter it says effective filtration :2.64 ft deign flow rate 52 gpm pressure lost at design flow rate 2.6 psi, max work pressure 50 psi that's all I could make out on the label hope that helps

[aylad]

The aqua chem test isn't going to read chlorine levels high enough, accurately enough, to fight the mustard battle. You can force it to read chlorine levels higher than 5.0, but you'll have to test from a diluted sample, and you'll lose some accuracy with each dilution. Does your aqua chem set test for CYA?

[CarlD]

Jan's right. I suspect your CYA / Stabilizer level is 0 (check the pool store readout). You're going to need lots of chlorine to fight and kill the algae. Your best bet is either bleach, or, if you have it available, 12% Liquid Chlorine. On gallon of 6% bleach will add about 1.7ppm of chlorine to your pool. A gallon of the Liquid Chlorine will add about 3.4.

If the pool is concrete, tile or other similar material, you can really hammer the chlorine levels without risking damage to the pool. If it's vinyl, it's a balancing act, depending on the level of stabilizer. Look for our Best Guess table for levels of chlorine re: stabilizer.

[aylad]

Platinum,

We really recommend that new users spend a good bit of time reading through the forums so that they learn what we're all about before posting answers to questions. For example, we generally do not recommend algaecides except for polyquat, and even then only in certain instances. In most cases, the use of algaecides, if one doesn't understand what it's doing to the pool water, can actually make problems worse instead of better. This poster can kill the mustard algae by shocking to a very high level and holding that level until the mustard is gone, but first she must get a test kit that will measure chlorine levels that high. Please take some time and do some reading....

Thanks

[PlatinumPS]

Oh god, one of these forums huh...30 years in the biz, i know what I'm talking about. I get right to the point & take care of the problem. You seem like one of those pools guys that'll tell a customrr anythng just to get their kney. Then they call me a month later to fix what you messed up. I've had it with you people. New to the website, not pool care. Algaecides work great by the way. I recommend people like you to go back through your books or take a refresher course every couple years with a the new products coming out all tue time