Yellow/Brown dusty deposits that reappear repeatedly

[jstonemo]

Floc is flocculant. It is a product that you add to the water that allows really fine particles to stick together into larger particles that your filter can catch and remove from the water. You can get it a your local pool store.

[Rangeball]

I was unable to get a sample of the stuff. It vaccuums up very easily, and doesn't act like any algae I've ever seen, but I do suspect it's some form of algae.

Wierd, my CL levels and use rates haven't changed, I'm still getting the same readings. My PH has crept up to over 8, so I need to knock it back down to increase my CL effectiveness. Perhaps that's why it was able to get started.

We've also had almost zero swimming activity in the pool for the past two weeks, which is never good for ultimate circulation.

[jstonemo]

Well, I had the CL levels at 23 ppm overnight last night and I added Alum to the filter to act as a filter aid. I woke up this morning and checked the pool. It is almost totally clear and clean. The CL level dropped to 19.5 ppm overnight, so something was being metabolized. In fact, after adding the bleach last night to get the levels above 20 ppm, I was in the yard and could smell the chlorine smell half way across the yard.

I don't think that adding 6.5 gallons of bleach to 12,700 gallons of water would make it smell so strongly. I am assuming it was chloramines from something breaking down. I can hardly smell anything this morning and the CL is still high at 19.5 ppm. I am going to try to keep it up near 20 for the rest of the day just to make sure everything is dead.

[Rangeball]

Had you vaccummed the pool before you shocked? If not did the "stuff" change color post shock?

[jstonemo]

I didn't vacuum. I did brush the bottom to get it stirred up into the water hoping that it would be better exposed to the chlorine. I am going to vacuum tonight or tomorrow.

[matt4x4]

I found some pics and descriptions of algae, and in turn, have to say that it may well be "Mustard algae" and not quite this brown algae i read about the other day. Mustard algae is one of those algaes that becomes resisitive to levels of chlorine up to 5ppm very quickly and may need levels as high as 30ppm to effectively kill it according to several articles i found - also, lots of brushing is required to fully expose it to the chlorine. Since this seems to be common when the swimming load dies off, your water is being mixed up much less, allowing this algae to take hold easier and quickly become resisitive to your typical sanitary chlorine levels.
I am still trying to find some sort of reference that may connect brown and mustard algae - from their descriptions, it may well be the same thing, just different terminology from different sources.....

Another couple of comments about mustard algae I found:

Yellow-green algae or xanthophytes are an important group of heterokont algae. Most live in freshwater, but some are found in marine and soil habitats. They vary from single-celled flagellates to simple colonial and filamentous forms. Unlike other heterokonts, their chloroplasts do not contain fucoxanthin, which accounts for their lighter colour. They appear to be the closest relatives of the brown algae.

YELLOW ALGAE: A wall clinging variety, also called mustard algae, is usually found on the shady side of the pool. It is sheet forming, and can be difficult to eradicate completely. Once begun, a pool owner could spend the entire season fighting yellow algae; reinfection is common. This variety is resistant to normal chlorine levels and must be dealt with firmly. Hit it hard!


Yellow Algae Phaeophyta: (Also called Mustard Algae), It creates a slimy layer that guards it from sanitizers. When brushed, yellow algae is removed easily but returns quickly. Yellow Algae can set in on any pool or spa. Chlorine may slow its growth, but will not completely kill this strain of Algae. An algaecide must be used to effectively kill and prevent this Algae.


Yellow algae is sometimes called mustard algae and appears on the pool surfaces as a fine dust. Typically it is seen first on surfaces that don't receive direct sunlight. This algae is easy to brush off, but it frequently returns. Most pool experts agree that this type is the most difficult algae to control. Use Sustain Algae Destroyer according to label directions and thoroughly brush the pool surfaces. Cleaning the filter and other equipment is especially important in controlling Yellow Algae. Circulate continuously and back-wash the filter/clean the element as needed to maintain good circulation. When the problem is under control, backwash the filter/clean the element regardless of the back-pressure/flow rate. This will rid the pool and equipment of any algae that may remain trapped in the filter.


Yellow Algae - This grown on the walls and when using your nylon brush it will dust up into a cloud. This is distinguishing between the two types.

*
Brush your pool surface with nylon brush.
*
Add a pound of granular shock per 10,000 gal. At the same time put in several capfuls of yellow treat. (There are several brands on the market, yellow out, yellow treat etc.)
*
Circulate for half an hour then shut pool filter off for 23 hours.
Brush again before turning filter back on.
*
After filter has run for 24 hours CLEAN YOUR FILTER. (If you don't clean your filter, then the algae will re-infect your pool water and you will have to start all over again!).
*
Use a good non-metal based algaecide and this will help prevent yellow algae.
*
After using any kind of yellow out, yellow treat etc., be sure and do new test reading of your chemicals and readjust as needed



NOTE!!! - Above statements NOT entirely true - high concentrations of Chlorine WILL kill it off without the need of other chems - algaecide may help stop it from returning.





attached is a pic of what I found, if those steps are white and this stuff has set in good - like my pool year one, then this is definitely it.
Here's another link to a small pic and description that matches our issues.
http://www.poolgear.com/algae.html (am NOT pushing anything they sell, just here for the pic!)


OK, OK, That's enough now!! I gotta do some work!

cya!

[chem geek]

Well, I had the CL levels at 23 ppm overnight last night and I added Alum to the filter to act as a filter aid. I woke up this morning and checked the pool. It is almost totally clear and clean. The CL level dropped to 19.5 ppm overnight, so something was being metabolized. In fact, after adding the bleach last night to get the levels above 20 ppm, I was in the yard and could smell the chlorine smell half way across the yard.

Man, this stuff is incredibly hearty. You had earlier quoted a CYA level less than 30 since it was getting cloudy at 30 (you said maybe 25, but it could be even lower than that). An FC of 20 with a CYA of 20 is a disinfecting chlorine (HOCl) level of 2.1 while at a CYA of 30 it is 0.9 so this is well above Ben's shock levels in his table and is higher than my own guess at 0.5 being sufficient to kill algae. It would seem that the easier-to-kill green algae seems to get killed over about a week at disinfecting chlorine levels of around 0.2-0.3 (so 0.5 would be faster), but this brown stuff needs somewhere between 1-2 ppm of disinfecting chlorine to kill. Yikes! Those people with high CYA in their pools are going to have a heck of a time killing this stuff. At 70 ppm CYA, it might take 46-58 ppm FC to kill this stuff.

As for the chlorine smell, yes you probably were smelling chloramines as intermediate by-products since these are formed rapidly. Then they are more slowly broken down (releasing nitrogen gas) and the smell goes away. This just shows that this brown stuff contains either ammonia or nitrogenous organics.

Richard

[chem geek]

I do not understand the chemistry of vinyl liner fading so do not know exactly what level of chlorine will start to fade a liner. It has been written elsewhere on this forum that low pH does more to damage and fade a liner than chlorine, but obviously very high levels of chlorine can bleach dye out of most anything (as several pieces of my clothing with spots on them will prove -- I never wear anything good outside anymore when I dose with chlorine, no matter how careful I am).

Now that said, your CYA level of 40 will tie up most of the chlorine and in theory this chlorine tied up (combined with) CYA should not affect your liner, but I can't be certain of that.

I also do not know definitively precisely what level of disinfecting chlorine is needed to kill this mustard/yellow algae. It has also been reported elsewhere on this forum that using a polyquat algicide will help kill this stuff though generally the philosophy of this forum is to use chlorine whenever possible and save the extra chemicals only when needed (and this may be one of those times).

Refer to this chart and notice that to get 1-2 ppm of disinfecting chlorine (at a pH of 7.5) that appears to be needed to kill this algae, you would need (at 40 ppm CYA) somewhere around 25-35 ppm FC. Keep in mind that this will only give you the equivalent of 2-4 ppm FC if you were not using CYA, but again I do not know if this would damage or fade a liner (my guess is that it wouldn't if only exposed over a week or so -- a year, well maybe).

If you want to play it safe, you could try the polyquat algicide to see if that helps, especially if you are concerned with your vinyl fading. I personally don't think you'll run into a problem with the 25-35 FC level, but then again I don't have a vinyl pool nor your situation. If you do decide to go the "chlorine-only" route, start out at 25 and slowly work your pool up to 35 only if needed and please let us know what happens.

Sorry I'm not more definite about this.

Richard

P.S.
Your web-site is really nice!

[matt4x4]

Since I had to up my chlorine every august to 30-35 ppm when this stuff set in, I can tell you from experience that for the week or so that you need to keep the high chlorine settings, your liner will not fade, you probably get more fade from one month worth of sun.