Do I have Algae?

[Litespeed]

I opened the pool a few days ago and I noticed some brown sandy looking substance on the bottom of the pool. Most of it was along the seams of the vinyl liner. I vacuumed the pool and left it as is.
Today, I opened up the cover and saw the same brown substance. As some background, we're still not using the pool, the water temp is only about 55 degrees (this is MN!). I'm just still in the early stages of making sure the pH, chlorine and CYA are all at the right level. Obviously too cold to run the SWCG so that is off.

I added chlorine three days ago and tested it then. It was at 4. I tested it again today and it was 3.5. There was no combined chlorine either day. pH has stayed at 7.4.

So, the question is, is this algae?

See the attached pictures. The one picture shows the deep end of the pool and basically, how clear the water still is. The second picture is showing a little bit of the suspect brown substance near the top of the picture on the right hand side of the seam. Most of it is along seams, but some of it is just kind of "pooled" randomly around the pool.

 

[Shirker]

0.5 FC consumption in 3 days is pretty good (what is your CYA?). You water is cold and you have it covered.... If it is algae, could it be left over from the previous season?

 

[Litespeed]

CYA is 40. And, I have kept it covered all winter and so far this spring. I suppose it could be leftover from last year, but I didn't notice an algae problem last year either. One thought I had is whether or not it was basically leftover pieces of broken down leaves. I always seem to end up with plenty of oak leaves in the pool in the spring before cleaning it up and am thinking if they broke down in the pool during the winter and spring, would it leave this brown dust?

 

[duraleigh]

Dead algae. You have live algae suspended invisibly in your pool water. As the chlorine slowly kills the algae, the "carcasses" settle on the floor, piling up at the seams and now it is visible,

You do not have a high enough level of chlorine to eradicate it. SLAM the pool. Do it correctly and it will go away and not reappear unless you let the FC levels get too low.

 

[Litespeed]

Thanks! I’ll do that.
I was just surprised that I could get algae in cold water. Probably didn’t want to believe it. Plus it’s been covered almost 100 percent of the time since closing.

 

[Chrissykr]

I opened green for the first time this year. I always close on 10/30 and open 3/25 my water is in the 50’s when I open/close.

 

[Litespeed]

Before I SLAM the pool, I thought I'd double check - my chlorine level only dropped by 0.5 over the last 3 days (using the FAS-DPD test). I was under the impression that if I had algae, it would have gone down by much more than that over the 3 days. If that means it isn't alge, is it possibly pollen? Tree pollen is high in our area right now. (although I keep the pool covered but it's been windy lately and it rained one of those days).

Since we aren't using the pool yet and because it is too cold for the SWCG, I am only running the pump for six hours overnight and at low speed 900 rpms. If it's pollen, I'm assuming it would it help to pick the speed?

 

[duraleigh]

I hear you. SLAM the pool. I understand that there is some uncertainty but SLAMming the pool removes the doubt and gets your pool clear.

SLAM the pool

 

[aeh0603]

Before I SLAM the pool, I thought I'd double check - my chlorine level only dropped by 0.5 over the last 3 days (using the FAS-DPD test). I was under the impression that if I had algae, it would have gone down by much more than that over the 3 days.

The OCLT is a good test for determining if you have algae or not, but it has it's limits. If you fail the OCLT, you have algae (or other organics). In that regard it's a pretty definitive test. Unfortunately, the opposite is not true. If you pass the OCLT, that does not prove that there is no algae present. This is why the SLAM procedure has 3 requirements to pass and declare your pool algae free. OCLT is only 1 of those 3 tests. Clear water is the one you are not passing right now. Your water is transparent, but you have visible evidence of algae and should therefore SLAM to get rid of it. Overall your water looks pretty good, so it should be a quick SLAM.

 

[Litespeed]

Thanks for extra explanation. I tested FC this AM and it was exactly the same as last night's measurement. Still no combined chlorine either. Based on this feedback though, I'll SLAM it, just to be sure. You are talking about the pool in the first picture in this thread right?

 

[aeh0603]

Yes, I was referring to the first picture in combination with your description. Make sure you brush really well along that seam during your SLAM to make sure any algae in there is exposed to the chlorine and killed.

 

[duraleigh]

Hold on just a bit. Is there just ONE pool involved in those pics?

 

[aeh0603]

The picture of the green pool was not posted by the OP

 

[duraleigh]

Thans, aeh, I had a small Senior Moment!

 

[Litespeed]

Yes, my pool pictures are in the first post. The two "blue" water pics.
I SLAMmed it
We'll see how it looks tomorrow.

 

[Litespeed]

So I SLAMmed the pool two days ago. FC was 15 for three tests and today - this evening - it was 14.5. The CC was 0. Water is very clear.

The only weird thing was that I got a CC reading of 1.0 during the test this morning. Out of the several tests I performed (several before the CC reading of 1 and 1 after), that is the only time I got a CC reading above zero. I think I may have just messed up the test somehow.

 

[kewpie]

So I SLAMmed the pool two days ago. FC was 15 for three tests and today - this evening - it was 14.5. The CC was 0. Water is very clear.

The only weird thing was that I got a CC reading of 1.0 during the test this morning. Out of the several tests I performed (several before the CC reading of 1 and 1 after), that is the only time I got a CC reading above zero. I think I may have just messed up the test somehow.

Hi! I have sandy brown deposits too and it’s been a week of no improvement...did yours go away and not reappear? Thanks!

 

[Litespeed]

It has improved quite a bit. Yesterday morning there was much less when I brushed it again. Will be checking it later again today.
I thought the water was pretty clear before but it has really improved as well.

 

[Litespeed]

Update from this morning... still a bit of brown dust asking just one seam in shallow end and some when I brushed the pool again but very light.
Water is sparkling clear. FC treated at 15.5 which makes no sense unless I miscounted since prior reading was 14.5. I haven’t added any chlorine since first adding it once to start SLAM because it had stayed steady. CC was again zero.

 

[duraleigh]

Keep your pump running 24/7 and keep brushing that dead algae up into the moving water so your filter can capture it.

The endpoint of that FC test (and other tests) is when the last drop you put in makes NO FURTHER color change, you subtract that drop and the result is an accurate FC. That may account for your discrepancy.