small algae blooms

[392papa]

I've been getting small algae blooms on various places in my pool. i brush them off and they disappear in the water. The water is very clear. They only seem to start when weather gets hot(august). Before I met you guys I lost the pool every august now i seem to be able to keep it under control with a higher chlorine level. I shocked it a couple weeks ago up to 20PPM (4 gall-12-1/2% chlorine). My question is this.....Should I be keeping my chlorine higher then I do? Its been between 5ppm and 10 ppm every time i check it . It seems so high even by the best guess chlorine chart. my #s are FC-6 CC-0 TA-7.5 TA 90 CYA 90.

I keep my tri-chlor feeder on low settings and supplement with liquid chlorine. What am i doing wrong? I am afraid I will wake up to a green pool some morning.

I also just got a new sand filter,,,, when I don't use DE powder Back-pressure stays @ 19PSIG for weeks. If i add 1/2cup...it goes up about a pound then increases up to 30PSIG after a couple of weeks. I backwash and it returns to 19PSIG. is this normal or am I just adding and back washing DE?

Thanks guys

[Themadczar]

Based on your post my guess would be that your cya is higher than you think and therefore you are not using enough chlorine. If you are using trichlor continuously, then you are adding cya all the time. Since, normally, the only way cya gets lowered is through water replacement, your cya is probably always increasing. Over 100ppm is difficult to measure (and I've found that getting an accurate reading is difficult at best and lighting plays a role in the accuracy too.) So I suggest you stop using trichlor and begin chlorinating for cya over 100. Anyone else have other thoughts?

[392papa]

Thanks,,,I was afraid you would say that

[PoolDoc]

High chlorine is not necessarily a bad thing -- on the plus side, you'll probably be able to add chlorine to your pool just 1 or 2x per week!

But, you will need to raise your chlorine level right away -- those 'little blooms' can suddenly turn into a great big one, and cleaning green swamps is hard with high CYA.

Do this:

1. Add 8 gallons of PLAIN 8.25% bleach to your pool ASAP.

2. Brush the pool soon after adding the bleach.

3. Read the "Best Guess" page, linked in my blue signature block.

4. Consider either raising your borate (borax) levels to 60+ ppm OR lowering your phosphates to below 100 ppb (not: ppm). I would recommend going with 60 ppm borates. Doing either will make your pool more 'algae-resistant', but maintain a 60 ppm borate level is usually easier than keeping phosphates below 100 ppb . . . and adding borax does not cloud your pool.

The reason for doing so, is that, when your CYA > 100 ppm, it's difficult to maintain the very high chlorine levels necessary to eliminate mustard algae.

5. Plan to switch to non-stabilized chlorine. Practically speaking, you have 3 choices: bleach, cal hypo, or a SWCG. For now though, use bleach. With a sand filter, cal hypo is an option, but it takes a special application technique to avoid having problems with high calcium levels.

[392papa]

Ben, thanks for your help I do have a couple of questions though.....1)the pool store is trying to sell me chemicals to lower phosphates,,,, unless i misunderstood what i've read hear I thought those were a gimmick.
2) I do not understand borates ,,,,I thought that was just another term for alkalinity. 3) per the best guess chlorine chart should I go to 25 PPM?


Thanks Papa

[392papa]

just checked my log I noticed my test kit is almost exactly 1 yr old. I have kept it inside @~70F. Is there a chance my chemical are bad? Is there a good way to check them?

Thanks PAPA

[PoolDoc]

Phosphate removers are a gimmick, in several ways:
1. They are sold to everyone, even when they have obvious worse problems -- like low chlorine -- that aren't addressed.
2. Phosphate removers are sold together with phosphate INCREASERS, like most metal treatment products.
3. They are sold as a solution, when at best, they are an 'aid'.
4. They are sold without mentioning the problems they cause, like cloudy pools.

Like most high-margin supplementary products that are occasionally needed or at least helpful, pool stores seem to sell them because it's profitable to do so, not because they are 'worth it' for most people.

But, the products DO remove phosphates, and if you get phosphate levels low enough and keep them there, a pool's susceptibility to algae WILL be reduced.

With high CYA pools, dealing with mustard algae can be difficult, because chlorine levels up to 60 ppm can be required. This is not impossible, but it complicates things, and it's better avoided if possible. I mentioned borates as a preferred 'aid' because it's long lasting, and has no negative side-effects*. But we don't have a lot of data on how effective either borates or phosphate removers are, and if you (a) don't have a lot of phosphates in your fill water and (b) can stay away from metal treatment products and (c) pool store goop, it should not take much, to lower your phosphate levels and keep them low.



*There is some data that suggests it's possible that if (a) you have male dogs used for breeding purposes, (b) who regularly drink from the pool, that (c) the fertility of these dogs will be reduced. That applied to one member of the Pool Forum support team, who used to post here frequently.

[Watermom]

To address another of your questions ---- a pool kit that is one year old and has been kept in the house should be just fine. I have several kits older than that and I am still using them. The first thing that will usually go bad is the FAS-DPD powder but it will be obvious when it does.

[392papa]

Thanks for your advice everyone!!!

[392papa]

Not really a question ,,,just an observation for discussion if anyone is interested:

I got home today , the pool is clear,,no blooms. Threw the auto robot in to mix things up and tested the chlorine(added last night per pool docs advice..thank you). FC-11.5 CC- 0. everything is cool.


Saw the neighbor(engineer smart guy-handyman does it all) out and asked him how his pool was doing,,,,great he said. I just load the tri-clor feeder every week and throw a lil PH up in it every now and then no prob......Mind if I check you water with my new test kit? I ask him. His results were,,,,FC-2.5 CC-0 PH < 7(unreadable) TA? ( turned red with just the R007+008) CYA wayyyyyyyy over 100 couldnt see the dot and the water level was only about 1/2 way to 100.

We both have the same city water for fill.....the only difference is he has one of those cleaners that works off a separate pump and the tail swishes things around(polaris?) makes me wonder if the real secret to keeping pool water clean isn't just keeping the walls clean and things mixed up. I did walk around his pool and saw 1 small algae bloom(<10"sq). I did get an electric polaris robot last year and i use it at least once a week. Seems OK though it was expensive.

Would love to anyones view that would like to make a comment.

Thanks again....PAPA

[PoolDoc]

We both have the same city water for fill.....the only difference is he has one of those cleaners that works off a separate pump and the tail swishes things around(polaris?) makes me wonder if the real secret to keeping pool water clean isn't just keeping the walls clean and things mixed up.

You're probably describing a Polaris pool cleaner. And yes, those are very effective in controlling mustard algae -- and probably, most other types of algae.

The reason is simple.

Almost all algae begins, not as free floating particles, but as a biofilm. Biofilms are nature's way for bacteria, fungi and algae to get a foot hold, where none exists. They are enormously complex -- the top of lots of new PhD theses -- but are fairly simple in basic construction.

They consist of a slime layer, that allows food and needed gases in, and keeps bad chemicals (chlorine) and predators out, covering a community of various bacteria, fungi and algae living symbiotically . . . and even talking to each other (really! biofilm signaling is a very hot topic currently in microbiological research!).

Sweeping, brushing, wiping break the slime layer and expose the organisms. When you brush your teeth, you are using detergent enhanced brushing to remove a biofilm that accumulates on your teeth. The bacteria that cause cavities can't function well, without a biofilm's protection. Likewise, the community that makes up mustard algae can't function well, unless it's under a biofilm.

BUT . . . the biofilm associate with mustard algae is far, far more fragile than the biofilm associated with, say, black algae.

Thus, a cleaner like a Polaris, which operates daily, prevents mustard algae from ever getting a good start. The "1 small algae bloom" you saw in your neighbor's pool is probably a spot his Polaris usually misses.

SO . . . a pool with a Polaris can control algae with significantly lower levels of chlorine, than a pool without a cleaner.

Daily brushing will accomplish the same thing, but few people brush daily, or even, weekly.

[392papa]

Lesson learned , I will be getting the brush out more often....Thanks Ben!!