Another "Is it algae or is it dirt?" thread....

[Smykowski]

I included this in the Deep End (mods, feel free to move if appropriate) because I wanted to get into algae behavior.

Does algae go dormant during the winter? How does algae in a pool react to freezing water/freezing temps?

I've the the same issue as a lot of other people have had, and I had it last year as well (before switching to BBB). Sediment collecting in the uneven areas on the bottom of my pool. It also collects along the liner seams. When I touch it, I can't characterize it as slimy or gritty. Depending on the patch I touch, it could be one, the other, or both. It brushes/vacuums up easily, and "poofs" into a cloud of dust. So easily, in fact, that only a strong water current will make it "disappear", only to redeposit a few hours later. I can vacuum the entire pool, but it redeposits within a day. I don't know if it's a true "re"deposit or if it's new material dropping to the bottom.

One of the reasons I'm questioning pollen is that I've had a solar cover on for about 36 hours, and I haven't had any dirt/dust/pollen appear on top of the cover, but the bottom of the pool looks filthy again.

When I opened the pool, my CYA was about 65-70, so my shock level was 19. For about 4-5 days I never let the pool get below 22, and it spend most of the time between 24 and 26. I passed the OCLT and let it come down to maintenance range. The water temperature during all of this was in the mid 60s. My pool has never been clearer than it is right now.

Back to my original question about dormancy. I have white wedding cake style steps that I took out of the pool over the winter and just let them sit on the deck. Here's my theory: The algae has all along been living in or on the steps. Algae didn't die during the winter, only went dormant. During the shock process, I missed brushing it, and it was never completely eliminated. Now that the water is warming up, it is trying to multiply in that bad circulation area. As soon as it tries to live in my properly chlorinated water, it dies, settling to the bottom. The "original" colony is still holding on because it's stuck somewhere where my chlorine doses won't get to it (until it grows).

Thoughts?

 

[JasonLion]

Algae grows more slowly when it is cold, way way more slowly when it is really cold, but it never goes truly dormant when it is in water.

If it is accumulating while at shock level then it is dirt. If it only happens when FC is lower than that it is probably algae.

 

[Smykowski]

During the opening process while at shock levels last week, it accumulated constantly, which makes me think dirt. Experiment time...

We've got a relatively cold weekend forecast, so I'm going to leave the solar cover on until Monday morning. It's raining right now, so can't judge yet, but if dirt is a problem, I should see the exact same sediment spots on top of the solar cover in the puddles, correct?

 

[duraleigh]

It might be easier to take a sample and roll it between your fingers. Dirt will be gritty...algae will be slimy

 

[Smykowski]

It might be easier to take a sample and roll it between your fingers. Dirt will be gritty...algae will be slimy

That's the problem, I can't really tell. Yesterday and the day before, while swimming dove to the bottom to try to grab it. A third of the time it would dissipate before I could touch it. A third of the time it felt slimy, and a third of the time it felt gritty.

As I'm looking out my back window, the rain has left some sizable puddles on the cover. I'm going to leave it all weekend, and see if the same dirt/dust/pollen accumulates on top of the cover. If it does, problem solved - my neighborhood is dirty and I'll have to deal. However, if on Monday morning the cover is still clean (or much cleaner relative to the bottom of the pool), then there's obviously something else going on.

 

[solarboy]

There's also the possibility of it being "dead" pollen.

 

[savdoc2]

I have had this same issue for 3 years now. To complicate matters, I live on a dirt road with soy and corn fields all around. Very little dirt/dust/pollen/algae accumulates on the solar cover, but it does on the bottom of the pool. I have also kept yellow algae shock levels because that was a consideration as well with no change and 0 CC. My dirt/dust/pollen/algae dissipates before I can feel it as well.

 

[Smykowski]

My water is crystal clear, and with no bather load, I'm losing about 1ppm per day, during the day. I had the solar cover on for 4 days, and when I took it off, the bottom was filthy. Top of the cover was dusty, but not close to what the bottom of the pool looks like. I got a stockpile of chlorine for cheap, so I'm going to use it. I'll bring it up to mustard shock level for a day, brush everything, and see if that does it. I pulled the wedding cake steps out of the pool to scrub them with strong bleach-water, and this "dust" was tucked in the corners, so maybe it is a resistant type of algae.

I seem to remember a post (but for the life of me can't find it) of someone who had this exact same problem. No chlorine loss overnight, crystal clear water, but "dust" that wouldn't go away. This poster shocked for mustard algae, and the problem was solved. If that doesn't work, I'll accept that I live in a dirty area and deal with vacuuming a little more often.

 

[Smykowski]

Update....

CYA is 65, brought FC to 44 at 3pm. Retested at 9pm and it had fallen to 34. Added more bleach and retested at 10, went to bed with FC at 39.5. Woke up this morning, FC was at 39. Still passing the OCLT, but 10ppm in 5 hours seems high. When I held FC in the 20s, I was only losing 2-3 per day. I understand that high starting levels mean a higher rate of loss, but going from 2-3 per day to 2 per hour seems like a bit much for just sun. However, it's puzzling that there's no overnight consumption.

Bottom does seem cleaner this morning, but it's really too early to tell. I'm going to test and maintain a target of 38-40 until mid-afternoon today, then let it drift down to normal. I'll vacuum the pool tomorrow morning, then I'm out of town for a couple days, so the real results will be when I get back. I'll let everyone know.

 

[brewtus]

I'm having this same problem. I opened my pool 2 weeks ago, and finally today, I noticed the material has returned.
I have fought with this for the last 2 years with no success. I've vacuumed to waste (seemed to stay away longer, but still returned), backflushed and rinsed my sand filter more often, and still, the problem returns.
Is it possible that the material is so fine that it passes thru the sand filter? There is no sand or grit in this, as soon as it is disturbed, it 'poofs' away.

My neighbor who had his pool installed last year, and has a cartridge filter, has yet to have the problem in his pool. This leads me to believe that this is a problem with sand filters unable to filter out this fine material.

 

[chem geek]

You could try to Add DE to a Sand Filter to improve filtration if you believe that is the problem.

 

[brewtus]

You could try to Add DE to a Sand Filter to improve filtration if you believe that is the problem.

I'll look into this. Much cheaper than a new filter and plumbing. Thanks.

 

[Smykowski]

@chem geek - I tried putting a nylon over the return while I vacuumed this stuff up last week, but nothing got caught. Usually it vacuums up just fine, but the pool floor only stays clean for about a day. I also tried DE in the filter, which polished the water nicely, but didn't solve the "sediment on the bottom" problem.

A little more info on my experiment....I pulled the steps again and got them as clean as they're going to get. The more interesting thing is my Pool Frog dispenser. Two years ago I decided not to use it because of the expense, so I put the dial to the lowest setting and just used the powder and tablets. However, I never pulled the dispenser from the return line. I opened up the cap yesterday, and realized I never took out the mineral reservoir or the chlorine pack. The chlorine pack is long since empty, but the mineral reservoir sounded like there was still stuff in it (hopefully all "worn out", that way its not adding stuff to the water). I immediately pulled both of them out and threw them away, but lo and behold, I think there was a yellowish/brownish something clinging to the bottom. I poured a little bleach in there and sealed it back up (I don't really care if I destroy it, cause I'm replumbing it within 6 months).

Fast forward to this morning, and there's a fine layer of junk underneath the return that has the pool frog. Because the dial was all the way low, there wasn't very much water circulation going through the canister, so I think the algae was living in there for 3 years. As it multiplied and hit the water flow into the pool, my correct chlorine levels in the pool immediately killed it, and it settled to the bottom. Except for the area under the return, the rest of the pool seemed to be cleaner than before, and I'm not sure if it was the thorough cleaning or the 24 hours at mustard shock level that helped.

I vacuumed the pool this morning, and it's as clean as I can make it. I'll see what it looks like after a couple of days and I'll report my results.

 

[Smykowski]

Final results...

Problem isn't totally solved, but there is significant improvement. After being gone for 4 days, there is still sediment/debris settling in the low points, but not nearly as much as before. I guess I'm glad I did the process, because I definitely cleaned something up, but I wouldn't say I found a magic bullet.

 

[brewtus]

I vacuumed my pool Friday afternoon to remove the spots of sediment. As of tonight, I haven't seen it show back up either. Keeping my fingers crossed.....

 

[Sasha]

I am intrigued by this conversation, Because I, too, have this same exact problem!!! Did it finally clear up or are u still dealing w the matter on the bottom? I also live on a dirt road in the country surrounded by trees.

 

[savdoc2]

My "green dust" is back. Weather is extremely dry. Corn in the fields is tasseling. FC levels have never dropped below 5. CC levels are 0. I think it is pollen/silt mixture.

 

[brewtus]

I usually vacuum the pool every Sunday, but was unable to do it this weekend, hence I had a rather large build up of this stuff.
Yesterday I vacuumed to waste every spot that I could find. I opened the sand filter up and cleaned it out the best I could.
I then used a garden hose with water running and 'probed' the filter to see if I had a channeling problem. There was a ton of material coming from the sand so I continued to flush/probe. When it seemed that the material was thinned as much as I could get it, I closed the filter back up and backwashed it. I then followed with an extended rinse.

Today I checked the pool when I came home from work, and it looks like I had never vacuumed the pool at all.
My numbers are FC-3 CC-0 CYA- 60 pH- 7.6 The sand in the filter is only 3 years old.

I'm debating whether or not to change the sand out, or just buy a cartridge filter.

 

[lka674]

I have what appears to be yellow staining on my tanning ledge and hubby said he saw algae down there, but before shocking for mustard algae is there a way to KNOW? It very likely could be pollen bc we have a huge crate myrtle that had been looming over that end of the pool till we cut it back last week....but I see these "stains" on the side gunfire too right under the tile rim. I can't rub anything off to see if it's gritty or slimy either....if it is pollen staining is there a way to remove that? Maybe the test would be to clean first for pollen stain and if no fix, then start shock process for mustard algae?

 

[nanalowe]

this is for smykowski...did you ever decide if it is algae or dirt? I had my above ground pool drained, scrubbed and refilled at the beginning of summer. About a week later what looked like a reddish-orange dirt had settled in low spots on the bottom. My water was clear, all the numbers were good, so I thought it was from the very hot, dry weather we were having. I have "waste" vacuumed 6 or 7 times to no avail. I thought maybe it was dirt because it would just seem to disappear when we swam only to settle after we got out. This was with the filter running continuously. Now I'm not so sure it's dirt and there seems to be even more. Even when the numbers are good, I was wondering if an algae can still grow. I would like to get this cleared up before I close the pool in a few weeks. Thinking about having a pool service come out just to look at it. I can't really afford it but I am getting desperate. One question: If I carry some of the water to have it tested will the stuff show up unless I stir it up first?