Mustard algae or pollen?

Aug 19, 2018
30
Deer Park/NY
Pool Size
23760
Surface
Vinyl
Chlorine
Liquid Chlorine
I know there are several other posts about this but after reading them all I still just can’t tell if what I have is mustard algae or simply pollen or dirt/sand. Here’s my current test results:

TC:
CC:
PH:
TA:
CYA
CH: (been told that for my vinyl liner that this doesn’t matter)

The water is clear and I can see the bottom all around. In the shallow end I always get these areas of what I always thought was dirt/sand. They always settle in low dips in the liner or next to a wrinkle. I have this a little in my shallow end which is where I get the most sun and can tell where the low areas and wrinkles are but I definitely have more of it in my deep end. I always just thought that this stuff settles more in the deep end because obviously it’s lower than the shallow end so the sloped side walls made the stuff settle at the bottom and also I mostly thought it’s there more because that water isn’t getting circulated as well etc as no one is obviously walking down there. The thing is that I don’t ever have this stuff on the walls of the pool. I do see it at the bottom of the sloped walls that lead to the deep end but not on any straight vertical walls so that makes me think that it’s not algae. Also I do have skimmer socks on and often when I clean them off they have a green/gray/brownish discoloring/gunk of what I always thought was pollen on them. Does algae float along the top of the pool or only stays on the bottom/walls? I tried to scoop some of this stuff up off the floor of the pool and get it in a cup but it’s quite hard to do so lol. I think I managed to get some in a cup so I added bleach and it did get lighter so I wasn’t happy to see that ☹️ If it’s algae then it would continuously get worse and spread wouldn’t it? So for instance the small amount I have in the shallow end never gets any worse or spreads to cover more ground. Granted I’m vacuuming at least once a week but it’s my understanding that algae spreads quickly. Another reason I’m so torn on this is because the area where the stuff settles in the shallow end is in a low spot right at the edge where the slope to the deep end starts and it’s ALWAYS in this spot. I’m thinking that maybe it’s just a spot where my return jets aren’t circulating the top of the water as well and so the stuff settles there. I mean algae wouldn’t be wanting to always just stay in that spot would it? Even if I brush it away it always makes it’s way back to that spot which is kinda right smack in the middle of the pool/return jets. I don’t have a lot of trees around the pool and in fact only have one that is very large and is about 12-15 feet away by my deep end. So as I’m typing this I’m thinking that maybe if it is pollen then that’s why it’s only ever in the deep end and right at that edge before the slope to the deep end starts because that’s where the tree is located. When I try to touch this stuff it doesn’t seem slimy to me but it does disperse very easily even if I am walking nearby. As some of it is dispersing into the water I can def see some tiny particles in it that spread around on the ground so that leads me to think it is pollen. I just don’t want to go through the nightmare of treating for mustard algae if that’s not what it is. Is there some other way of telling? After vacuuming how quickly would mustard algae usually reappear? If left untreated how quickly would mustard algae spread?I just went out to look at the pool again and I just saw one of those backswimmer bugs in there. I know they feed on algae but I’m pretty sure I’ve read some posts on here about people that had backswimmers even though they didn’t have algae. I’ve attached some pictures of the before and after of the cup test and also some pics of the pool floor. In the one picture where I marked in red that is the spots that i said earlier that this stuff tends to settle in the shallow end. In the other pics where I marked in black those are stains on the liner so don’t think that’s a dirty area that I’m talking about. Sorry for this long, babbling post but I’m so confused and don’t know what to do. Please help!!!!
 

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What happens when you brush it?

Unless you also have pollen all over your cars, pool furniture, etc, it is not pollen. It is likely algae. Dead algae.
 
Hey Jenn !! Do you have any farms nearby ? I’m an hour east of you and they are stirring up quite the dust storm lately. It will look and behave like both pollen and algae. We can rule out pollen this late in the season so that leaves the other 2.

Perform an Overnight Chlorine Loss Test to know if there is anything growing or it’s just dirt.
 
What happens when you brush it?

Unless you also have pollen all over your cars, pool furniture, etc, it is not pollen. It is likely algae. Dead algae.
When I brush it it makes a little cloud of greenish color. So what do I need to do if it’s dead algae? Does that mean it won’t spread? Does that still require SLAMing to get rid of it?
 
So what do I need to do if it’s dead algae? Does that mean it won’t spread? Does that still require SLAMing to get rid of it?
Dead algae is what has died and consumed your FC (usually leaving plenty still alive).

2 things consume FC. The sun (UV) and organics like algae or swimmer residuals. If you do the overnight test you are removing the sun from the equation and with healthy water you should have no FC loss. If you have overnight loss, something, most usually algae, is in the water.

With no loss then we look to pollen/dirt as the culprit.
 
Hey Jenn !! Do you have any farms nearby ? I’m an hour east of you and they are stirring up quite the dust storm lately. It will look and behave like both pollen and algae. We can rule out pollen this late in the season so that leaves the other 2.

Perform an Overnight Chlorine Loss Test to know if there is anything growing or it’s just dirt.
Hi there!! No I do not have any farms nearby. I was thinking the same about the pollen but was just hoping that it wasn’t mustard algae 😫 lol. I performed an OCLT a few days ago to check for the same and the result was .5 loss. Just to play safe i started SLAMing the pool yesterday anyway and I did have to keep adding quite a bit of chlorine every hour or so to maintain the right FC. That makes me think the chlorine was being used up so quickly because it was indeed fighting something. Then again it was also a super sunny day yesterday. I did another OCLT last night and the result is 2.5 😳 so I guess there’s my answer. I’m not sure why it didn’t show a loss overnight the other day though. Could it be because the algae was on the floor the other whereas now last night it was more all over because I had brushed the pool? 🤷🏻‍♀️
 
. I did another OCLT last night and the result is 2.5 😳 so I guess there’s my answer. I’m not sure why it didn’t show a loss overnight the other day though
With only the first day, It’s real easy to mess up. With multiple tests you’ll get closer to the answer. *or* it got worse in the meantime.

OCLTs are super important. Always slow it down to be as close to routine as humanly possible. (Your hand will still have the slightest shake, none of us are robots).

The bottle goes completely upside down and the gentlest of squeezes will let gravity make perfect, repeatable drops. Again. Take your sweet butt time here. A mere 2-3 seconds per drop could make all the difference in the world in your answer.

Slamming is even worse. Somebody needs to make that same perfect drop 30-60 times in a row. Yeah, no kidding there is ‘test error’. (Wink wink). Lol.
 
With only the first day, It’s real easy to mess up. With multiple tests you’ll get closer to the answer. *or* it got worse in the meantime.

OCLTs are super important. Always slow it down to be as close to routine as humanly possible. (Your hand will still have the slightest shake, none of us are robots).

The bottle goes completely upside down and the gentlest of squeezes will let gravity make perfect, repeatable drops. Again. Take your sweet butt time here. A mere 2-3 seconds per drop could make all the difference in the world in your answer.

Slamming is even worse. Somebody needs to make that same perfect drop 30-60 times in a row. Yeah, no kidding there is ‘test error’. (Wink wink). Lol.
Oh wow. I NEVER do my chlorine testing that slow 😬😳 I will start to now though lol. Thanks!!

So today I’m having a few friends over and of course we want to use the pool so I was thinking to add more chlorine now to get back to SLAM level (it’s currently 15.5) and then let the chlorine lower itself a little in the afternoon. Is that ok or will I be going backwards then? I know it’s safe to swim as long as the FC is below SLAM level and the water is clear, I can see the bottom in the deep end so it’s safe to swim right? Then I was thinking that later tonight I can raise the FC back up to SLAM level and keep it there tomorrow and then hopefully I pass the OCLT test after that (Sunday night to Monday AM). Then at that time (if I do pass the test) do you suggest that I raise it to mustard algae level for 24 hours just to play safe? I’m going away for a couple days on Tuesday so if all goes well then I’d be leaving a nice clean pool which won’t even need chlorine added while I’m gone because it’ll be so high before I leave 🤞🏼🤞🏼🤞🏼🤞🏼🤞🏼🤞🏼🤞🏼
 
Is that ok or will I be going backwards then
A few hours off will be the same as if you ran to the store. Party on. Keep it mostly elevated and you won’t lose any ground. You can swim right up to SLAM level but giving yourself a bit of wiggle room there is never a bad idea. As you’ve seen, the testing *cough cough testER cough cough* can be a bit off.
I can see the bottom in the deep end so it’s safe to swim right
Correct. As long as you can find somebody, God forbid.
Then I was thinking that later tonight I can raise the FC back up to SLAM level and keep it there tomorrow and then hopefully I pass the OCLT test after that (Sunday night to Monday AM).
If not, the FC should be holding plenty long enough to go back to work on Monday.
Then at that time (if I do pass the test) do you suggest that I raise it to mustard algae level
Statistically speaking it’s usually not mustard algae, but it’s always a possibility. Up to you if you want to wait and see if it returns, needing the extra round. (And another mini SLAM).

Either way at SLAM or Mustard level you should be ok for a few day trip. Sometimes things just work out like that.
 

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It’s different for everybody. It could be a few days or a few weeks. This season for sure.
 
*also, From your logs you dipped under minimum several times. You rode the minimum line plenty others. And here we are.

Your regular testing/adding kept it from going full swamp, so +1 for you there.

If you target ‘in range’ as your minimum we will never speak again, unless you want to drop in and say hi. The initial raising to the higher level will cost peanuts. From there, maintaining the higher level does use more chlorine, but not a lot. You’d either not notice it, or barely notice it and still not care. We have a short season here and if you slip you can lose 1/3 of it. If you aim for your daily loss and ‘fall into’ target range each day, again, this will be the last time we discuss it. Lol.
 
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Yes you’re right. I was only testing the FC every other day and when I would test it was def on the low end or even under. I will be sure to test every night as to avoid this whole situation. It’s so true that a few minutes a day can really save hours of work and headache. Hey while I have you…my pool doesn’t have a deep end skimmer…do you think that can be a problem that the water down there isn’t circulating as much? I was thinking to connect my manual vacuum and let it sit in the deep end once a week for at least a few hours…think that will help?
 
I assume you mean not having main drains ? Many pools don’t have them and they are not needed for circulation. Think of all the above ground pools that are almost 5 ft deep and are deeper than the average in ground pool with a 3 or 3.5 ft shallow end. They all circulate fine with no main drains. :)
 
Right but then again those 5 foot pools have more manual circulation because swimmers are walking around the entire thing whereas obviously no one is walking in my deep end or even swimming anywhere near the bottom…I thought maybe it made a difference. Seems to make sense in my mind 🤷🏻‍♀️😆
 
Seems to make sense in my mind 🤷🏻‍♀️😆
Your brain is SPOT on. It’s completely true that above grounds have people walking on the bottom and stirring it up but they sit empty the overwhelming majority of the time just like the rest of pools.
 
So my OCLT was about 1. I would’ve liked it to be less.
Personally I like to ‘pass’ with flying colors. But ‘Cs’ get degrees they say. :ROFLMAO: It’s all a matter of personal preference.

The reason why a loss of 1 passes is mostly to allow the user a little leeway for human error. Let’s say the FC was 8. You’d have to make 16 perfectly perfect drops. We all rush at times and have a shaky hand at other times. There could also be a small amount of swimmer residuals left over from the kids swimming all day. Or it could be the early warning sign of a bigger loss down the road.
Do you think I should keep my FC at the higher end of range?
I personally do, yes. If you know your pool backwards/forwards you may dance that minimum line as close as you wish. Maybe you enjoy the challange. Some folks do and others are just so frugal that they want to save every drop. Nobody is wrong, but targeting high gives you lots of leeway while you learn.

Many of us started that way and once we saw how well it worked, never stopped.

It’s like if you wanted to really get to know me. We’d talk every day and you’d just know how I felt about the daily news. Maybe every month some new info would come out and you’d have to find out how that changed my usual thoughts. Just like the pool season. It changes dramatically over the season from low demand early, higher and higher demand, and then waning demand for FC as the season winds down. But day to day is almost unnoticeable. Talk to your pool every day and you’ll know it well. :)
 
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Do you think that high (SLAM) FC level has any effect and could cause the OCLT to not be as accurate? The kids didn’t do any swimming. In fact no one has swam in it since Saturday since I’ve been keeping it very consistently at SLAM level and even on Saturday there was very little swimming being done. I was excessively (OCDish lol) on top of testing every 60-90 minutes and adding more chlorine to maintain that SLAM level so I find it really hard to believe that there could still be anything in there (except of course unless it was actually mustard algae ☹️).

Back to the deep end…when you say “drain” do you mean that it’s not like a skimmer where it draws in water to the filter and helps with circulation?
 
Do you think that high (SLAM) FC level has any effect and could cause the OCLT to not be as accurate
Totally. Let’s take your SLAM level of 16 FC. You need to make 32 perfect drops to get the accurate 16. It becomes less and less likely with more drops. If one drop is off in size, it won’t matter much. If 10 are off…. Yeah. So we tell folks to ride the SLAM for a few days once everything else looks good and then let the FC drift back down to see if it holds. It usually does.

But we want stupid clear water first. Invisible even. You’ll know it when you see it.
Back to the deep end…when you say “drain” do you mean that it’s not like a skimmer where it draws in water to the filter and helps with circulation?
A skimmer has a door that opens/closes and whooshes the water in every few seconds to force any floating debris nearby into the skimmer where it gets trapped in the basket. A main drain (s) on the floor only have suction. They both move water but have 2 different functions. The main drains help some but really aren’t needed. They don’t have much pull, even on full pump speed. A robot or manual vac does a far better job of removing debris that fell to the bottom.
 

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