Mustard Algae or Pollen/Dust

Aug 3, 2012
10
Hello all! Long time lurker, first time poster.

I woke up last week after a bad thunderstorm left a branch in our pool. I removed it, vacuumed, brushed, etc. That day I noticed my FC was at 1.

I've since brought my FC up to 25 (with bleach). My problem is that my water is a very light green color.

I was reading about mustard algae and how it grows on the sides and in the shade. In my pool there is some dust looking stuff on the bottom. It brushes off relatively easy and it kicks up dust and clouds up the pool.

My question is if you guys think it's mustard algae, pollen, or something else.

FC: 25
PH: 7.4
CYA: 60
TA: 250 (I know this is high, but the pool was fine before)

Any advice is appreciated. I haven't tried the overnight chlorine test due to me not having a high end kit. I've been using the dilution method to get a best guess of my FC, which has been about 25-30.
 
Welcome to tfp, blemast3r :wave:

Is the "very light green color" clear (and just a tint) or cloudy?

It does not sound like mustard algae. It could be pollen or possibly algae on the bottom. Does it feel slimy?

Post some pictures of it.

Can you vacuum to waste?

Doing a OCLT would be the best way to determine if you have algae, but will be tough for you since the dilution method reduces the accuracy of the test.
 
linen said:
Welcome to tfp, blemast3r :wave:

Is the "very light green color" clear (and just a tint) or cloudy?

It does not sound like mustard algae. It could be pollen or possibly algae on the bottom. Does it feel slimy?

Post some pictures of it.

Can you vacuum to waste?

Doing a OCLT would be the best way to determine if you have algae, but will be tough for you since the dilution method reduces the accuracy of the test.

Thanks for the reply linen!

The light green color is pretty clear (just a tint) until I start brushing or get near it and then it becomes cloudy. I tried to get a feel of it when some of it was settled on the bottom but it kicks up when I get near it.

I'll try to post up some pictures when I get home from work. I can vacuum to waste but I haven't yet. I've been trying to brush twice a day and vacuuming to filter.

I've tried adding a 1/3 cup of de to my sand filter but my pressure goes high and I lose water flow within an hour. Should I keep doing this and backwashing when I lose water flow?

I'll also try to feel the debris again once it settles down to the bottom.

Thanks for trying to help!
 
After a few days of hitting it hard with bleach (about 15 gallons over the last few nights) and brushing/vacuuming I'm seeing significant improvement. The green tint is virtually gone. The water is a bit cloudy and there is very little settling at the bottom of the pool.

My question is my ph reads at 8.2. I know that the PH readings can be inacurrate due to the high FC levels. My FC is at least over 15 (can't get an accurate number until my Taylor kit arrives.) Should I add some muriatic acid to get the ph down to the recommended levels? Or should I just wait until my new test kit arrives and get more accurate numbers?

Thanks.
 
As you said, ph reads high when above 10 ppm FC, so do not adjust. If you are concerned, let your FC drop below 10 ppm briefly and measure/adjust ph then. Most times this is not necessary. What was your ph before stating the shocking process?
 
The kit shipped today and should be here later this week. Since I can't do an overnight loss test yet do you recommend that I keep adding bleach nightly even though my pool is starting to clear up?
 

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The kit came in today and I tested the water first thing. Here are my results:

FC: 15
CC: 0
PH: 7.7
CYA: 70 (could be 65, still learning this kit)
TA: 300
TH: 310

The pool is sparkling clear now. No signs of algae or anything else. Should I do an overnight loss test to be sure? Should I still not worry about PH since my FC is still above 10?
 
Okay. I did the OCLT.

FC last night was 13.
FC this morning was 12.

We had a lot of rain throughout the night so I'm not sure if that would have any effect on the test or not. The water still looks great. Just gotta go fish out the leaves that fell in due to the rain.

Should I perform another OCLT to be safe?
 
blemast3r said:
Should I perform another OCLT to be safe?
I think the one you did was sufficient. My experience with rain is that it only cause more FC drop and not less.

Was your CC below 0.5 ppm?

If it was, I would let your FC drop down to the normal range (5-10 ppm per poolcalulator.com and 70 ppm cya). Keep an eye out for returning algae...if there is/was mustard algae, it likely will show back up on the walls/floors where there is shade.
 
Yeah the CC was at a 0 this morning. I'm gonna monitor my levels closely over the next week or so. Hoping that everything is in order. Thanks to this great forum for all the insight and help. Consider me a BBB loyalist now.
 
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