Yellow algae won't go away!

Hi all. Now that I've taken care of my filter problem, I have to deal with the constant yellow algae that is in my pool. A lot of it is "stuck on", no matter how many times I brush or vacuum it. I keep the chlorine floater filled and run the pump roughly 8-10 hours a day now. It's still too cold to swim in (~60 degrees), so I can't get up close and personal with a smaller brush. What should I do to get rid of it? I've seen posts about using bleach and muriatic acid and the like. My pool is 25,000 gallons.

Hi Kramer. You'll need to provide us with a current set of water testing results taken with a drops-based kit for someone to be able to help. If you don't have a good test kit, you need one. The best one you can buy is the Taylor K-2006 or 2006C which you can get through the Amazon link in my signature below.

A floater filled with trichlor tabs is not going to take your chlorine level high enough to attack algae. Once we see some testing results, someone can better advise you. Also, tell us more about your pool.

I'm guessing you haven't tested your stabilizer level?*

Mustard algae is resistant to chlorine, but goes away (slowly) when you follow the Best Guess chart 'shock' levels. But, those are determined by stabilizer level.

Order K2006 -- or at least a CYA test that uses liquids and a disappearing dot, and find out what your CYA level is. Once you know what your stabilizer level is, you'll have to set your chlorine level accordingly, or drain and refill, which is pretty wasteful. However, if your stabilizer is above 60ppm, you'll need a DPD-FAS kit to test chlorine levels.

So, the best thing really would be to get a K2006 (boy, we say that a lot!), which has both a CYA test and FAS-DPD testing. (Link in my signature) Do NOT overdo the CYA testing with the K2006 -- it only comes with enough reagent for 6 tests or so. But, you don't need to test more than 1x per month, so that should be fine, if you just are careful.

Meanwhile, if you've been using stabilized chlorine, get a cheap OTO/phenol red kit, and keep your chlorine in the DARK yellow range, till you have a CYA test results

* 'Guess-strips' don't count! They aren't very accurate at best, and they are at their worst when it comes to CYA measurements.

OK. I actually found a bottle of testing strips in my pool area that measures chlorine, PH, alkalinity and stabilizer. Here's where we're at:

chlorine: maxed out at 10 ppm
PH: between 6.8-7.2
alkalinity: between 120-180 ppm
stabilizer: between 150-300 ppm

As Ben indicated in his post above, test strips aren't really too accurate. We really need current water testing results taken with a drops-based kit. Do yourself a favor and get that Taylor K-2006 kit that Ben recommended AND in the meantime, pick up a cheap OTO/Phenol Red (red and yellow drops) kit. Your pH could be below 7.0 which is acidic and can damage your pool. We also need to know your CYA level which was done with the disappearing dot test to be able to recommend appropriate chlorine levels for this pool. Take a look at the Best Guess Chlorine Chart in my signature below. If your stabilizer (CYA) level truly is over 150, then you're going to need really high chlorine levels to kill this algae. And, the only way to measure those really high chlorine levels is with a FAS-DPD kit which is what the K-2006 is. Other test kits can't read high enough to help you.

I'll see about getting the K-2006 this weekend. In the meantime, I have one of the red/yellow testers and did that as well. Chlorine is still maxed out, and the PH is right at 7.2.

The problem here is that you may need to have your chlorine more than "maxed out", depending on your stabilizer level. If your CYA really is 150, then your chlorine has to be in the OTO orange range (20 - 40 ppm), which is not shown on your kit.

Also, if you are waiting to get the K2006, when you go to a local store . . . Don't! It's very, very rarely available locally, and they'll often try to sell the K2005 which is NOT the same, and NOT what you need. If you don't want to buy at Amazon, that's fine, but you will need to order online.

Alright, I got a free water test from my local Leslie's over the weekend, and here's what they found.......

calcium- 560ppm (!!!!!)
CYA- 100ppm
alkalinity- 90ppm
pH- 7.4
phosphates- 20ppb

Obviously, I need to do some draining and re-filling to get the calcium hardness down. What else would anyone here recommend?

The calcium is not a problem UNLESS you have scaling. In California, you'd better test your fill water, before assuming that draining and refilling will fix things.

You *need* a K2006. But, stop-gap, check and see if you have a Walmart in your area that has this kit:
http://www.walmart.com/ip/HTH-6-Way-Test-Kit/17043668
This is a private label custom Taylor kit, that's compatible with the K2006 . . . and it will allow you to get a reasonable CYA level, now.

Meanwhile, keep the chlorine HIGH (OTO => orange!), and brush. Do NOT use any more stabilized chlorine. Get your FILL water tested (or, better, get the K2006 -- here's the info page: http://www.poolforum.com/pf2/showthread.php?14994) before you think about draining.)

Also, please post your pool info in your signature, here: http://www.poolforum.com/pf2/profile...=editsignature so we don't have to keep looking through the thread to see what sort of pool you have.

Do NOT drain, till you've tested your fill water. Do NOT drain, if you have an AG, vinyl or fiberglass pool. Doing so incorrectly can DESTROY those pools.

I got my fill water tested. Calcium came out at 80ppm.