Identifying sediment; fighting algae; & OCLT

[Opus4]

Is there a place to send a sample of sediment to finally determine what this stuff is?


I've looked at it under a microscope & I see round objects... but then when I check pollen & algae photo samples, what I see seems like it could be either. The sample I put in a container still has the sediment in the bottom & the water doesn't look any different than when taken out of the pool several days ago.

In the past, it has been fairly obvious when algae was growing because the pool got cloudier. In the past, I've hardly ever had CC over 0.5 or an OCLT drop more than 1. So, when I did have algae, the only way I could tell for sure was water that steadily grew a bit more cloudy every day. Now for weeks, the water has been clear enough to read from across the 30' pool while underwater, if my eyesight happened to be good enough for that, and the FC & CC tests have been fine. I can't even remember the last time CC was above 0.

That all seems to indicate just pollen/dust, but I can't help wondering, especially since my FC & CC tests in the past didn't really indicate algae even when it became obvious that something was growing. If it is algae, it sure is a slow growing type. Maybe the recent rains here in NJ have brought in a lot of very fine dust.

Whatever it is is too small for my cartridge filter, since the pool is only cloudy after trying to vacuum. Once it settles, it is perfectly clear again. This sediment question is the only thing about taking care of my pool that has me stumped & it seems to be a fairly common topic here.

Again: is there a place to send a sediment sample to? Thanks.

 

[Bama Rambler]

Re: Somewhere to send sediment sample?

I don't know of any place to send a sample to. My bet is that it's dust.
What happens to it if you squirt a little bleach in the sample of it?

 

[crumtastic]

Re: Somewhere to send sediment sample?

Is there a university near you? You might be able to get it tested there...

Have you tried the sock trick? Just put a white sock over the return with a rubber band, if needed to stay on. I was having problems with sediment that was getting through my sand filter and the sock caught all of it. Now I use the sock every time I vac and it's cut my vac'ing from every other day to once a week.

 

[Opus4]

Re: Somewhere to send sediment sample?

Thanks for the comments.

I don't know of any place to send a sample to. My bet is that it's dust.
What happens to it if you squirt a little bleach in the sample of it?

I haven't tried that yet; will add it to my list.

Is there a university near you? You might be able to get it tested there...

Have you tried the sock trick? Just put a white sock over the return with a rubber band, if needed to stay on. I was having problems with sediment that was getting through my sand filter and the sock caught all of it. Now I use the sock every time I vac and it's cut my vac'ing from every other day to once a week.

Now that you mention it, Rutgers is essentially right around the corner. I'll have to look into that.

Yes, I've put filters over the return. Things are definitely getting caught there - that was one way I knew it was getting past the cartridge filter.

I mentioned rain earlier -- we've had 5+ inches of rain recently. The sediment is worse now compared to last week... I wonder if the rain brought in very fine particles. the water vapor has to have something to condense onto when forming clouds.

 

[crumtastic]

Re: Somewhere to send sediment sample?

I'm betting that it's the rain bringing it in. I always have to vac after a lot of rain.

 

[Opus4]

Re: Somewhere to send sediment sample?

Wouldn't you know it: right after I give up trying to determine what the stuff is myself & ask here whether someplace offers a service to identify the stuff, the pool finally started turning slightly cloudy a couple days later. I think whatever is there just grows slowly & finally got to the point that it overwhelmed the chlorine level -- for CYA of 30 - 35, I've been keeping the FC between 4.5 & 7 (it never tested below 4.5 for weeks). CC has never been > 0.5 & is almost always 0.

I had a similar problem last year, but at that time, I figured that the hollow stairs had bad circulation & were a safe zone for algae; they've since been removed. This year, I don't know where it could be hiding or coming from, but I'll just shock & take care of it. Other 'dusty sediment' topics have mentioned shocking at mustard levels & finally getting rid of it, so that sounds like a plan to me.

Did I read that mustard algae likes shade? I only recently started using a solar cover again (yes, it was clean; in fact it was new, since the old one was coming apart) because the weather was too hot to use it for a while & now that I think about it, the sediment seemed to increase when the cover was on earlier in the summer & now vs. when it was off for a couple weeks.

 

[Beamup]

Re: Somewhere to send sediment sample?

Yes, mustard does like the shade. Normally this manifests as appearing mostly on the more shady sides of the pool, but I guess the solar cover thing could fit too.

Keep in mind that with mustard, you need to not just shock, but brush EVERYWHERE - light niches, inside the skimmer, everything. The stuff likes to hide out in crannies (the shady thing again), forming biofilms to resist even the mustard shock FC level, and then come right back as soon as the FC goes back to normal. You have to get in everywhere and brush everything to break up those biofilms and expose everything to the chlorine so it can be killed.

 

[Opus4]

Re: Somewhere to send sediment sample?

Keep in mind that with mustard, you need to not just shock, but brush EVERYWHERE - ... inside the skimmer ...

Thanks for that reminder -- I had thought of (hopefully) everything else, but forgot about inside the skimmer. Things I can clean will be cleaned; things like foam noodles are going away.

 

[Opus4]

Re: Somewhere to send sediment sample?

I've been trying to search the forum for this: the mustard algae instructions say to keep FC at mustard shock levels for 24 hours after passing the OCLT at regular shock level. But, mustard shock level has produced the first OCLT where the FC drop was > 1. I assume that means the mustard shock level will need to be maintained for more than the suggested 24 hours, right?

 

[duraleigh]

Re: Somewhere to send sediment sample?

I assume that means the mustard shock level will need to be maintained for more than the suggested 24 hours, right?

Correct. Shocking completely means holding the FC at shock value until....

1. Your water is crystal clear.
2. You lose less than 1.0 FC during the OCLT
3. Your CC's test is .5 or less

If you are asking whether to hold it at mustard value or normal shock value I would suggest the higher mustard value. Clearing the pool has been troublesome for you so holding the higher value will help it clear more quickly and thoroughly.

 

[Opus4]

Re: Somewhere to send sediment sample?

If you are asking whether to hold it at mustard value or normal shock value I would suggest the higher mustard value. Clearing the pool has been troublesome for you so holding the higher value will help it clear more quickly and thoroughly.

Yes, that's what I was asking, thanks. I guess I was just leery of keeping the higher Cl level for a longer time, but it does seem to be more effective since anything lower never had a > 1 OCLT.

 

[Opus4]

Re: Somewhere to send sediment sample?

There was actually more FC loss last night than the first night. But, that should mean some progress since at normal shock levels FC didn't drop at all overnight. Between a storm coming through now & Irene hitting us this weekend (though weakened compared to the Caribbean & southern US), the pool will probably be getting quite a bit of rain water added to it. Not sure what that will mean for the OCLT, but it does mean the sun isn't eating all the Cl during the day.

 

[Opus4]

OCLT question

Here's a question regarding the OCLT: the general rule is to consider everything to be fine if the loss is < 1.0. But, is that loss proportional to the amount of chlorine in the water?

For example: in the middle of a sunny day, over the course of an hour, I believe I've read that the chlorine loss from a starting point of 10 ppm would be higher than if the Cl started the hour at 5 ppm. Is that correct?

If yes, then out of curiosity, if there were no organics in a pool, could the overnight Cl loss be higher when the night is started at a much higher Cl level than normal? (If there are no organics, I don't know what would even cause the Cl loss overnight -- can it react with anything else in a pool or even evaporate in some form?)

 

[Bama Rambler]

If the water were hot you might lose a little but the 1 ppm criteria accounts for that. As long as there are no organics in the water it really doesn't matter what the starting FC level is (within reason). You won't lose it any faster at 20 ppm than you would at 5 ppm.

 

[Opus4]

If the water were hot you might lose a little but the 1 ppm criteria accounts for that. As long as there are no organics in the water it really doesn't matter what the starting FC level is (within reason). You won't lose it any faster at 20 ppm than you would at 5 ppm.

Thanks; I had started to wonder since the percent overnight loss at MA level could have translated to < 1.0 at a much lower Cl level.

The good news for me, anyway, was that the OCLT test last night resulted in just about the exact same test results at 10 PM and 5:30 AM -- the results of FC = 13.5 & CC = 0.5 had just about the same level of light pink for those last FC & CC drops each time. So, I should finally be done.

After Irene (lost 1 small pine tree), I did another full set of tests & the main change was that CYA went from 30-35 to < 20. That's either from the pool's water loss due to 9+ inches of rain or something had been eating my CYA. So, my new MA shock level went from ~22 to <14. Results while cleaning the pool from Irene:

FC: 7.5
CC: 0
pH: 7.4
CH: 60
TA: 70
CYA: <20
Borates: ~15.

While cleaning the pool of twigs & leaves, I added bleach, bumped the TA to about 90, & added boric acid for about 50 ppm borates. In the evening, I bumped up Cl & ended up passing the OCLT.

Next, I'll re-heat the pool, add more CYA, and finally go back to swimming. I appreciate all the info on the forum & pool school.