What kind of algae is this?

[mcarter]

Does anyone know what kind of algae this might be? It seems to mostly stay on the bottom, not exactly green in color, and pretty resistant to shocking treatments. I've been staying on top of chlorine levels but did go through a few cycles with dry acid trying to adjust my alkalinity. It seemed like every time I brought the ph down to 7.2 these algae would show up, so maybe a result of the lower ph?

 

[Newdude]

Hey M !!
How are you testing ? Most shock-y folks are doing so at the pool store and asking them what ails you *and* for the cure is a silly decision anywhere but the Dr.

Take my old fuel oil contract with a National company. (Stupid stupid stupid). They gave me a FREE yearly tuneup saving me $175. Woo woo. But if I was blowing black smoke out my chimney, they sold me more oil so guess how well they maintained my furnace. When I figured it out a few years later my buddy whom I brought in was throwing things mad about how little was ever cleaned in my furnace. So yeah. Pool stores are exactly like that and we need our own reliable test kit to all be on the same page. I have and swear by the tf-100 from tftestkits.net. The K-2006C can be bought many places but was $100 more recently when I checked so to spend more on the 2nd best kit (although still a good kit) is silly. Check the current prices and go from there.

We will gladly guide you if you have good data.

For starters, all that shock raised your CYA which means you need more chlorine in a daily basis to keep algae at bay. Shock some more and the FC need goes up again. At some point algae wins the battle and moves in.

Secondly, a 10 FC or above skews many PH tests to be high so if you were recently shocked, you PH tests may not be valid.

 

[thetekgeek]

This has nothing to do with the lower PH level. You need to follow the SLAM process and you'll need a quality test kit to do that. How are you testing your water? How have you been chlorinating the water?

You'll want to order a good test kit. Read this: Test Kits Compared - Trouble Free Pool

While you're waiting for your test kit add only liquid chlorine (bleach) to the water, nothing else. Use PoolMath to calculate the amount of bleach you need to add 5 ppm worth of free chlorine and add that amount each day until your kit arrives, this will help the outbreak from getting too much worse until you have the kit and can properly SLAM.

You also need to read this - SLAM - Shock Level and Maintain - Trouble Free Pool

Also, consider reading all of the chemistry related articles in Pool School - Pool School - Trouble Free Pool

Those are the beginning steps. The experts on this site will be here to answer any questions you have along the way.

 

[JamesW]

It's likely to be mustard.

SLAM Process

 

[mcarter]

Thanks, Yes I already have an HTH 6-way test kit and test weekly, sometimes daily. Also, use those test strips to get an idea of FC level.

My chlorine level is kept in the range of 5-11 ppm and CYA at 80 ppm (Recently abandoned Trichlor). No CYA was added, I've been chlorinating with liquid chlorine (bleach) and shocking with the same. I get a good deal on the 12.5% stuff at my wholesale pool supply store.

Also using the TFP app on my phone.

-Mike

 

[mcarter]

I've also slammed twice in the last month, using 12.5% sodium hypochlorite according to the TFP pool app and it did not knock out the algae completely or it came back in a few days. That's about 1.7 gallons of chlorine per shock treatment! As I said, my CYA is at 80 ppm, as a result of using Trichlor and reduced from like 120 ppm after doing a partial drain.

That said the water is staying clear, and it's not too bad otherwise.

 

[Newdude]

, Yes I already have an HTH 6-way test kit

That will work for CYA, PH, TA and CH but the drop test for FC is about as reliable as a test strip. (Not reliable at all). Nor can they read over 10 ppm to properly SLAM Process as you’ll likely need.

order a fas-dpd powder test kit to be able to run the full suite. A smart stir is worth it’s weight in gold to do all the mixing for you. You haven’t LIVED until you own one. Trust me there. Best $30 I spent on the pool.

test weekly, sometimes daily

No bueno. No bueno at all. Or…..

and it did not knock out the algae completely or it came back in a few days

bingo. When we are through this you will test daily until you have a unison of zen with your pool. Then you can test every other day. Occasionally every 3 days but only on occasion.

 

[mcarter]

Thanks. Right, I meant a full test weekly (pH, Alkalinity, Hardness, etc), but I do check chlorine daily or at least every other day.