Mustard Algea

red-beard

Member
May 27, 2019
16
Houston, Tx
Hi. My name is James. And I have Mustard Algae

First...Yes, I am fighting CYA buildup. I drained the pool this year. Completely! And I added enough stabilizer for 30 ppm. I did not understand how much stabilizer is in the Tri-Chlor 3" tablets and used them for about 6 weeks. I have now have an 80 PPM CYA level (as measured with a Taylor 2005 wet kit). I'm trying to keep the Free Chlorine level around 8 ppm. I use a Taylor chlorine titration kit for chlorine level.The issue is sunlight.

I am using Cal-Hyp tablets now. They are 8 oz each and take 4 days to dissolve. This means I'm adding 4 oz of cal hypo per day. This adds to chlorine level by 0.75ppm/day. I'm using cal-hyp 53% powder as a supplement as needed.

My pool has no shade. Sun starts to hit the pool about 8AM and does not go away until 6PM. Yesterday, I lost 2 PPM, net (8 yesterday morning, down to 6 PPM today). So sunlight is taking about 2-3 PPM/day. But on a cloudy day, the Chlorine level increases by about 1 PPM (as I would expect with the Cal-Hypo tablets).

If my Level gets to 6PPM or less, the Mustard starts to grow. I'm mostly controlling by trying to keep the level to 8PPM and brushing twice a week. But even then, I might see a little mustard forming in certain areas that do not get a lot of water flow.

I certainly can do a partial drain to get back down to 30-50 PPM. Not sure how this will help with the chlorine usage from the sunlight. I saw notes that higher levels of sunlight (like Houston) need higher stabilizer levels. But I can't find any charts on this.

The rest of the levels: I keep the Ph Between 7.4-7.6 (muriatic acid), TA = 110, CH = 200-210 (low on purpose as I'm using Cal Hypo), CYA 80, Borate 50, CSI -0.02, Temp 86 F.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
I would agree with Marty. :goodjob: In our areas, a summer CYA of 50 is almost mandatory, and in some seasons I've gone up to the 60-70 range. But a CYA of 80 is pushing it and a bit high in my opinion which, as you already know, requires a higher FC level as noted on the FC/CYA Chart. The lower CYA will allow you to perform the SLAM Process at a lower FC level. I would find a place locally where you can obtain liquid chlorine (aka regular bleach) and use that exclusively. I was using HEB's Bravo for years until they reduced its strength to 6% but kept the price the same. :mad: Just shop around for other places like Home Depot, Walmart, etc that have liquid chlorine (regular bleach) to avoid adding by-products like calcium or stabilizer.

Have a great 4th! :salut:
 

IceShadow

Gold Supporter
Jun 8, 2019
1,070
Milwaukee, WI
Ok so:
- Exchange about 30% of water and get down to 50 ppm CYA
- Get pH to 7.2
- Take FC to SLAM levels for 50ppm and run pump constantly
- Brush and re-test often, at least 3 times daily and up to once an hour, keep adding chlorine (liquid chlorine) to get to SLAM levels
- once pool is crystal clear and under 1ppm CC, do an overnight chlorine loss test nightly until it passes
- once passed bring FC up to Mustard Algae levels and hold there for 24 hours, brushing EVERYTHING often
- let FC fall down to standard maintenance levels
 
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red-beard

Member
May 27, 2019
16
Houston, Tx
I'm reading a lot on CYA and will be doing ANOTHER drain and refill this summer. According to some sources, CYA can absorb in the plaster. I did not check my CYA level before adding my initial dose to 30PPM. Also, by my calculations, my Triclhlor additions should only have brought the level to the mid-60's. I think there is some truth to the retained CYA. I expect my levels were 200+ before draining, since I went two years with Tri-Chlor without a drain. Previously, I went 10 years using tri-chlor without a drain and refill. Man that stupid stuff is insidious.
 

red-beard

Member
May 27, 2019
16
Houston, Tx
Again, doing a lot of reading here and according to Chem Geek, there are times to go above 50PPM CYA. My pool is on the southside of my house, in Houston, in full sun from 8AM to 6PM, and around 92F (really need to put up the sail shade!).

At 80 PPM CYA (if I'm reading the Taylor "black dot" test correctly), I am losing about 2-3 PPM Chlorine per day. For the past week or so, I raised the Chlorine level to around 8-10 PPM (I'm now targeting 10PPM for my nightly addition). I brushed on July 4th and MAYBE (or MAYBE I'm paranoid), I thought I saw a little mustard coming back after 4 days. I brushed last night (July 8th) and raised to 10 PPM (moving to nightly additions instead of morning). I have minimal overnight loss, maybe 0-0.5PPM. At this level of Chlorine, I'm using the 10ml FAS-DPD test, which is accurate to around 0.5PPM. My FC this morning was 10 PPM and CC was 0.

I switched to 10% liquid CL from Home Depot, which has eliminated my need for HCL additions. If things continue OK, I'll probably keep my 80 PPM CYA until I change to Salt. If not, I'll do a drain and SLAM. I also ordered more FAS-DPD reagents, since it it going fast...
 

Texas Splash

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TFP Expert
LifeTime Supporter
Our scenarios are almost identical. HOT! After this years's HEB (Bravo) bleach % reduction, I switched to HD's 10% this season as well. Our pool is on the west (hot) side, full sun from dawn to dusk, with water temp pushing 96 (ugh). While I haven't had to do it yet, many times I raise my CYA to 60-70. I do know of other non-salt TX owners who push their CYA to 80, but do so knowing the risks ahead of time and ensure their water is algae-free first. But that is key.

That CYA test is critical for sure. If you chose to ride on the high end, continue following the target values on the FC/CYA Chart. If later you do see algae or fail an Overnight Chlorine Loss Test, you know you have the option to exchange water to lower the CYA (pre-SLAM) which, perhaps as an added bonus, should lower your CH as well if that is a problem.

CYA Testing:
Proper lighting is critical for the CYA test, so you want to test for CYA outside on a bright sunny day. Use the mixing bottle to gently mix the required amounts of pool water and R-0013 reagent, let sit for 30 seconds, then gently mix again. Recommend standing outside with your back to the sun and the view tube in the shade of your body at waist level. Then, begin squirting the mixed solution into the skinny tube. Watch the black dot until it completely disappears. Once it disappears, record the CYA reading. To help the eyes and prevent staring at the dot, some people find it better to pour & view in stages. Pour some solution into the viewing tube, look away, then look back again for the dot. Repeat as necessary until you feel the dot is gone. After the first CYA test, you can pour the mixed solution from the skinny view tube back to the mixing bottle, gently shake, and do the same test a second, third, or fourth time to instill consistency in your technique, become more comfortable with the testing, and validate your own CYA reading. Finally, if you still doubt your own reading, have a friend do the test with you and compare results.
 

red-beard

Member
May 27, 2019
16
Houston, Tx
CH isn't an issue. I'm only at 210. I raised it to 200 and then it has raised with the use of the Cal-hyp (tablets and powder). I could have continued using the Cal-hypo, but it definitely changes the pH. Looking at the cost of the HCL plus Cal-hyp, I'm better off just using liquid Cl. As I said, my "plan" is to switch to salt later in the year, just don't have $1K for the system plus salt at the moment.
 
Last edited:
Our scenarios are almost identical. HOT! After this years's HEB (Bravo) bleach % reduction, I switched to HD's 10% this season as well. Our pool is on the west (hot) side, full sun from dawn to dusk, with water temp pushing 96 (ugh). While I haven't had to do it yet, many times I raise my CYA to 60-70. I do know of other non-salt TX owners who push their CYA to 80, but do so knowing the risks ahead of time and ensure their water is algae-free first. But that is key.

That CYA test is critical for sure. If you chose to ride on the high end, continue following the target values on the FC/CYA Chart. If later you do see algae or fail an Overnight Chlorine Loss Test, you know you have the option to exchange water to lower the CYA (pre-SLAM) which, perhaps as an added bonus, should lower your CH as well if that is a problem.
Texas Splash, what kind of CYA degradation do you see with your water temperatures so high? I’m on the other side of San Antonio from you and have shade in the afternoon, so my temperatures aren’t so high. Last summer, though, when they were in the 90’s, I found myself surprised when I had lost CYA and then had to add more so that my SWCG could continue to keep up. I was reassured when I read posts on the forum that said it does degrade very slowly but the pace may accelerate at higher temperature (and maybe chlorine levels?). I was wondering if you thought that red-beard might lose some over the summer just because of heat and maybe rain in Houston.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Texas Splash, what kind of CYA degradation do you see with your water temperatures so high?
In the heat of summer, I may expect to lose maybe 10-20 ppm of CYA over the entire span of say Jun - Sept. In fact I just cranked-up my own CYA today and need to grab more to reach my summer 50-60 range. The heat is that intense in my area. The rain would only be a player if we removed water ahead of time to fill with fresh water. Dilution no so much.
 

Lemonred34

Well-known member
May 5, 2019
155
Louisiana
In the heat of summer, I may expect to lose maybe 10-20 ppm of CYA over the entire span of say Jun - Sept. In fact I just cranked-up my own CYA today and need to grab more to reach my summer 50-60 range. The heat is that intense in my area. The rain would only be a player if we removed water ahead of time to fill with fresh water. Dilution no so much.
Totally off topic.....but being in Louisiana I always thought our summers were miserable. Hot and humid, just overall miserable! UNTIL...I visited San Antonio the end of July one year. I vowed to never complain again! I legit burned my arm on the seat belt buckle. Not an “ow that burned” but had to have it treated 🤣 so I feel for you guys!
 
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red-beard

Member
May 27, 2019
16
Houston, Tx
Update: I spent the past week raising the overnight chlorine level to between 9 and 10 (about 1/2 gallon of 10% liquid chlorine per day). It is dropping to 7-8 during the day. I have not brushed since Monday and I do not see any mustard growth, so far.
 
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