CYA over 100 with yellow/mustard algae

[MikeM]

OP here with a quick update. I was able to procure a pint of Orenda PR10000 for a reasonable price online, $24 plus $6 shipping. I've been dosing over the last several weeks. In theory, I should have only needed 5.7oz to reduce my 18kgal pool by 1000ppb. After two quarts of the Clorox product, plus 12oz of the PR10000, I'm still at ~300-400ppb phosphates. I just added the last 4oz of the Orenda product to see if I can get a little closer to 125ppb. Either my water was a lot higher than 1000ppb or these products remove far less phosphate than indicated on the label. I've had very minor clouding for about an hour after each dosing, then it clears up by itself. I used no clarifier. The pressure on my cartridge filter has gone up *maybe* 2psi. Anyway, I've been at this since mid July, and still don't have the phosphates down where I want them. I still have the yellow algae although it's less noticable... could be the lower phosphates or the lower water temps. CYA is 37 and I've been keeping FC in the 6-10 range.

[MikeM]

Just another quick update... It's been one week since I added the last 4 oz of PR10000. The phosphates are right at 200 ppb. The effectiveness of this Orenda product is no where close to what's indicated on the label. Anyway, I'm done for this year. The water temps are down in the mid 70s and the yellow algae still returns, but much more slowly than before. After brushing, it takes about 3-4 days to notice the algae (vs 1-2 days previously), and it's a much smaller growth than before... probably some combination of lower phosphates and lower temperatures. FC consumption is steady at 2.5 ppm per day. My cartridge filter pressure is at 19 psi, up from 12 psi after the last cleaning in May, which is maybe 2-3 psi higher than it would normally be, absent any phosphate removal process.

[JimK]

Thanks for the update.

That's disappointing that the PR10000 isn't near as effective as advertised. I've been keeping an eye on this thread should I ever decide to lower phosphates.

Edit: I just noticed I've been upgrade to "Verb Herder". Hmmm...is that a complement or an insult...lol.

[FormerBromineUser]

I am disappointed too. Congrats on the Verb Herder! You're in the Big Time now, buddy!

[PoolDoc]

Richard - ChemGeek - uses PR10000 and reports that PR10000 *does* remove PO4 as predicted.

But . . . what I'm seeing myself (I'm using it) suggests that it only does so AFTER you have lowered PO4 levels fully. What I suspect is that there are more phosphates in the pool system -- pipes, pool surface, filter media -- than there are in the water itself. This would not be surprising, since phosphates are often.added to water in the first place because of their abilities to attach to surfaces. If I'm right, then the attached phosphates will only be released back into the pool water when the PO4 levels begin to get low (< 500 ppb?).

My guess is that attached phosphates will be low in all plastic pools with cartridge filters (plastic liner, plastic pipes, plastic equipment), but high in concrete or stone pools with sand filters.

I would strongly encourage you, if you've reached 200 ppb, to go ahead and get that next quart. 200 ppb is NOT low enough to be very helpful, but it's very, very close to 100 ppb, which IS low enough. If you stop now, you are sort of like someone who started a 10k run, but stopped at 9.8k.

[PoolDoc]

I should add, that I'm seeing a consistent MAJOR improvement in mustard algae control, when PO4 levels are at 150 ppb or less.

By improvement, I mean that the mustard algae is MUCH slower growing, and MUCH less chlorine resistant.

[FormerBromineUser]

How's it going?

[MikeM]

OP here with another update. Well, I still had the yellow algae all winter, despite maintaining FC in the 6-10 range with CYA around 30. I did buy a second pint of Orenda PR10000. I've now used all but about 3oz over the last several months, but phosphates are still hovering around 300-400ppb. Over the last 12 months, I've used 2 quarts of a Clorox product and now 2 pints of Orenda. According to the labels, this should have removed several thousand ppb. There is no phosphate in my source water and no other obvious source. I read PoolDoc's explanation of "attached" phosphate with much interest, so I'll keep trying.

Another oddity, same as last year, my CYA mysteriously dropped like a rock to zero in the Spring. I've added some CYA to get back to about 30-40. I have a cartridge filter and don't lose much water normally, so I don't understand this loss of CYA. The pool was running all winter and water looked fine except for the recurring yellow algae.

In any case, I'm now holding FC in the 10-15 range since April and sweeping several times each week. I'm also running the polaris about 3 hours per day instead of my normal 1 hour. So far, no yellow algae, but this could be because the polaris and I are sweeping it up every day. I'll cut back sweeping and see what happens this week. I'll also use the last 3oz of Orenda, but based on my experience, I'm quite certain that will have no effect on phosphates in the water.

If any other suggestions, please let me know. Here are my numbers from this morning:

FC=13.5
CC=0
pH=7.6
TA=90
CYA=35
CH=280
Borates=50
PO4=400