5 year dedicated TFPer totally stumped!

[Pauls234]

All,

I've been stumped the 2nd half of this pool season with dead algae settling on the bottom of my pool within 3-4 days after vacuuming. I've been a dedicated TFPer for 5 seasons now so I know that, more often than not, this is actually a chemistry issue rather than one of filtration, but I have done so many things and am pretty confident that I've ruled out chemistry and concluding that it is filtration, so I need some further advice.

Here is how I've reached my conclusion:

My water remains TFP clear - guests come over and at first glance think the pool is only half full. I know TFP clear water, and I have it. But junk (dead algae I believe) settles on the floor throughout the week, I vac Saturday morning and it's clear all weekend, until Wed/Thursday when it starts to show up. This has been ongoing since early July. I am not in a dusty area, so do not believe this is external.

To rule out chemistry issues, I bought some of the R-7065 about a month ago to confirm my CYA. This stuff looks like more like 35-40 to me and not 50, and my pool water looks like 35-40 to me as well, so I've been assuming 50 for my CYA level. Went through the SLAM process (including brushing) passed the OCLT the first night, but continued for another day, passes the OCLT again. I test regularly and have not seen chlorine usage outside of expectations - losing only 1.5 or a bit less on days (usually going from 8ppm to 6.5ppm) with no swimmers, and maybe 1.5 - 2 on days with swimmers. I have run OCLT somewhat regularly and never fail, often showing no loss overnight. My regents are new this season.

Since I began treating my CYA level as 50, I have never let my chlorine level drop below 6, never. CCs show up only occasionally, and it is always 0.5 or lower.

I've checked the usual suspects by removing and brushing the stairs, and leaving them out for an extended period of time. The only light I have is on the return. I've also left the pump running non-stop for weeks at a time to see if that changed anything. It did not.

I use a cartridge filter, media bought new early last season. I've inspected it for tears, holes, etc and see nothing. I am very careful about ensuring that it is seated properly as well. When I take it out to wash, I do notice that it feels slimy in places, could algae be somehow surviving inside the filter at an extremely low level?

The only other hypothesis I've come up with is maybe the filter housing is so old that the seating is out of round and thus dead algae sneaks through over time and gets sent back into the pool?

What else can I do to try and diagnose the source of this? My next step would be to purchase a new filtration system, or at least replace that old fiberglass housing that scratches me up every time I break it down.

Any thoughts? Something else that I did not think of? Please help!

Paul

 

[JVTrain]

How often are you brushing the pool aside from the weekly vacuuming? In addition to vacuuming, you should be manually brushing the pool once per week as well, especially during the warmer months. I've had a similar issue last year, water was crystal clear but if I let the pool go 4 days without brushing or running the robot, I would see similar small piles of algae. I started brushing at least once per week and running the robot, twice per week during July and August. No more issues. Like you, I passed an OCLT immediately after bringing FC up to SLAM levels.

Regular brushing is part of distributing chlorine everywhere in the pool and not allowing algae to get started in dead spots in circulation.

 

[JoyfulNoise]

Can you put a Slime Bag over the returns to try to capture the stuff? Being able to capture it and inspecting it can you a lot about whatever it is (sand/dust versus dead algae).

How is you water balance (CSI)? Could this possible metals or calcium scale?

Algae would be very strange to develop in you pool since you are carefully managing the chemistry levels.

 

[Pauls234]

Thanks for the thoughts gents.

Joel - I admit that I have not been brushing weekly. And there are definitely dead spots in circulation, however, wouldn't swimmers solve the circulation problem if that was the cause? I'll try anything at this point, but want to understand if you are suggesting this might be a circulation issue vs. other benefits of brushing??

Matt - I honestly have not paid much attention to CSI because 1) I have a vinly pool 2) My fill water is soft (from Lake Michigan) and I do not use products that add Calcium and 3) when I started TFP I don't recall CSI being part of it all! But, playing with some numbers (haven't tested Calcium for a while) I would be well within -.6 to +.6 range.

I'm pretty confident it is dead algae, when I get close to look at and touch it, it is green, not grainy in feel, very slightly slimy and vanishes in a poof when I touch it. I believe I had a minor algae out break earlier in the season, water was dull, never green, and speculate that I fell below the minimum when I was treating my FC targets as though CYA level was 30-40, rather than the 50 that is now suggested by my R-7605 comparison. I just can't determine if it is new dead algae or the same stuff just recirculating.

 

[JVTrain]

There is really no substitute for brushing. A good robot that's run a couple times per week can almost do it, but there's nothing better for a pool surface than a physical brushing to make sure that there are no areas where algae can get a foot hold. Every pool is going to have dead spots in circulation or not optimal circulation, perhaps leading to local zones of reduced FC levels. No big deal at all if these areas get brushed and attention at least once per week. I wouldn't say it's a "circulation" issue persay, just that all pools require physical brushing at all surfaces in contact with the water regularly.

 

[JoyfulNoise]

There is really no substitute for brushing. A good robot that's run a couple times per week can almost do it, but there's nothing better for a pool surface than a physical brushing to make sure that there are no areas where algae can get a foot hold. Every pool is going to have dead spots in circulation or not optimal circulation, perhaps leading to local zones of reduced FC levels. No big deal at all if these areas get brushed and attention at least once per week. I wouldn't say it's a "circulation" issue persay, just that all pools require physical brushing at all surfaces in contact with the water regularly.

+1

In my pool, I run my suction side cleaner all the time except when swimming. It's just easier to leave it in the pool and forget about it then to have to put it in and out all the time. Given that, my pool water is constantly being agitated in random and different ways by the cleaner constantly moving around on the floor. I do want to convert to a robot someday but I have often wondered if my pool's cleanliness would be significantly impacted since I would be removing the "constant" source of vacuuming and replacing it with an intermittent one.

It is an odd thing though that you are experiencing because you seem to have a source of algae and yet it is killed quickly and piles up. So where is the source of algae? Do you have old pipes or places in the pool that could be harboring a colony of sessile algae that is constantly growing and shedding and then winding up dead in the pool? That would be a very rare occurrence considering you've eliminated a lot of the normal sources of hidden algae (lights, ladders, etc).

Any chance you could cover your pool and see what happen?

 

[jwhop3]

Doesn't algae need sunlight to grow? It would have to be somewhere visible, right?

 

[Pauls234]

I had the solar cover both on and off for extended periods of time and the results were unaffected.

Ok, so sounds like you both believe it is much more likely to be an algae problem than a filtration issue.

So, my plan is as follows:

Twice a week brushing for a couple of weeks
Twice a week running of the suction side vac

I'll report back results, sound good? Anything else?

 

[Pauls234]

Vigorous brushing has been done once and will be done this weekend with a thorough vacuuming as well.

One thing occurred to me, as I approach closing and water temp is cooling (though I will likely crank up the heater and get at least one more swim in) will this mysterious algae problem be solved in the winter freeze? Or does algae lay dormant only to re-awaken with the spring?

 

[triptyx]

+1

In my pool, I run my suction side cleaner all the time except when swimming. It's just easier to leave it in the pool and forget about it then to have to put it in and out all the time. Given that, my pool water is constantly being agitated in random and different ways by the cleaner constantly moving around on the floor. I do want to convert to a robot someday but I have often wondered if my pool's cleanliness would be significantly impacted since I would be removing the "constant" source of vacuuming and replacing it with an intermittent one.

It is an odd thing though that you are experiencing because you seem to have a source of algae and yet it is killed quickly and piles up. So where is the source of algae? Do you have old pipes or places in the pool that could be harboring a colony of sessile algae that is constantly growing and shedding and then winding up dead in the pool? That would be a very rare occurrence considering you've eliminated a lot of the normal sources of hidden algae (lights, ladders, etc).

Any chance you could cover your pool and see what happen?

I do the same, and for the same reason. I'd rather have something in there vacuuming every day without my intervention than have a robot I have to put in/pull out.

 

[ping]

My neighbor's above ground pool was having the same issues as yours and it turned out to be his ladder and it was full of algae. You might want to inspect it if you have one.

 

[JoyfulNoise]

Vigorous brushing has been done once and will be done this weekend with a thorough vacuuming as well.

One thing occurred to me, as I approach closing and water temp is cooling (though I will likely crank up the heater and get at least one more swim in) will this mysterious algae problem be solved in the winter freeze? Or does algae lay dormant only to re-awaken with the spring?

Algae will not be killed during the winter, only dormant. That's why the recommended closing procedure has you SLAM the pool prior to closing. If you close cold (water <60F) and open early (water at 60F), then any surviving winter algae should be easily killed.

 

[Pauls234]

Ping - I have inspected all of the usual suspects over the last 2 months, including removing my stairs, brushing them and leaving them out for weeks at a time with no change in results - totally clear water but a slow accumulation of dead algae on the floor.

Matt - It is amazing how well that works. I have done such every season and have always opened to clear water, and usually even test FC at around 5 in the spring when I remove the cover.

This is why I am so baffled by this ongoing issue, but I will see how the more regular brushing goes.

 

[JoyfulNoise]

I'm not an algae expert but is it mustard algae? M/A typical requires a SLAM and then a high mustard algae shock level for 24hours. Is it brownish yellow colored (greenish closer up) and develops in piles on the bottom in shadier parts of the pool?

 

[JoyfulNoise]

Does it look like what is in these two links -

Greenish Dirt or Algae on bottom of pool

Any idea what this is? How to remove?

 

[Pauls234]

you know, I never suspected mustard algae, because it seems like one of the more common false positive on the forum, but you might be on to something.

It is definitely a greenish brownish color, it does look a lot like pics in that second link. It tends to settle more heavily on the side of the pool away from the return, so where circulation is least and it matches the characteristics as described by JamesW in that second link. It doesn't "develop" anywhere that I see, just shows up dead on the bottom and water remains clears as I described.

So I think mustard algae SLAM is in order. I thought I once saw a chart showing a higher SLAM level for mustard algae, or is it same level, just maintain that level for several days following SLAM?

 

[Catanzaro]

Once you are done with the Mustard Algae SLAM and if the problem still exists, IMHO, this is clearly a circulation issue, with a lot of dead spots. Frequent brushing is a must. A few questions:

1) How many hours per day do you run the filter and at what times?
2) Do you have a skimmer and one return close to each other?
3) How many other returns do you have in the pool and how far apart are they spaced out?
4) Some AG pools have main drains. Do you have a main drain?

I am a big fan of the circulator return jets (I have 4 in the pool) and then there are 2 V Fusion return fittings. The water is moved pretty quickly all over the place. Thanks!

ROTATING HEADS FOR A SWIMMING POOL

Amazon.com : The Circulator - Automatic 360 Rotating Swimming Pool Cleaner Return Jet with deep heating and chemical infusion : Swimming Pool Maintenance Kits : Patio, Lawn Garden


The Circulator Rotating Water Jets for Swimming Pools - YouTube

 

[JoyfulNoise]

you know, I never suspected mustard algae, because it seems like one of the more common false positive on the forum, but you might be on to something.

It is definitely a greenish brownish color, it does look a lot like pics in that second link. It tends to settle more heavily on the side of the pool away from the return, so where circulation is least and it matches the characteristics as described by JamesW in that second link. It doesn't "develop" anywhere that I see, just shows up dead on the bottom and water remains clears as I described.

So I think mustard algae SLAM is in order. I thought I once saw a chart showing a higher SLAM level for mustard algae, or is it same level, just maintain that level for several days following SLAM?

See here - Chlorine/CYA Chart

There's a mustard algae shock level for 24 hours after the SLAM is complete and then you have to maintain your FC at the higher mustard algae level.

 

[kimkats]

OH main drain! I notice my pool was losing it's "TFP Sparkle". I did some looking, testing, thinking, back tracking. I found I had forgotten to open the valve to my main drain the last time I ran my cleaner! So that water was just sitting in there with no movement. I opened the valve and squirted some chlorine down it and did a quick SLAM. All was right in the world in about two days...........my TFP sparkle was back! :sun:

Just something to look at and think about.

 

[Pauls234]

Ok, I raised to shock level and vacuumed up the dead algae and leaves, then brushed every square inch. Water remains TFP clear by the way. Assuming I pass the OCLT (which I have never failed throughout this ordeal), I will then raise to mustard shock level tomorrow morning, brush again, and keep it there for the next couple of days and see if it solves the problem. No doubt cooling water will help, and perhaps even give me a false sense of resolution, it is about 65 now.

Catanzaro - thanks for the thoughts and links, I wondered that myself, but if circulation were the issue, then I feel like I should have had this issue before. It is a big pool though and given the persistence of this nuisance, I do not rule anything out. Answers to your questions:


1) How many hours per day do you run the filter and at what times? - typically 8am-noon, then 7-10pm (but have experiemented with 24 hours with no change in results)
2) Do you have a skimmer and one return close to each other? - Yes, about 18 inches from edge of skimmer to return
3) How many other returns do you have in the pool and how far apart are they spaced out? - Just the one return
4) Some AG pools have main drains. Do you have a main drain? - No main drain

- - - Updated - - -

and thank you Kim, you are very creative when it comes to thinking through these things so please stick with me if this does not resolve the issue!