How to know if its pollen or algae that's making my pool pale green?

Erin R

Bronze Supporter
Mar 14, 2019
22
Tallahassee, FL
Hi there - I'm hoping for help differentiating between pollen and algae in my 28,400 gallon SWG pool. It's been pale green for two weeks, coinciding with a heavy pollen fall. The water is cloudy but translucent--you can see through it to the bottom, especially in the shallow end, but the entire pool has a distinctive pale green color. It's not thick or opaque, as I've seen in a past outbreak. I'm worried it's algae, but could this just be pollen? It doesn't smell much different.

I've raised the chlorine level from 6 to 12 and backwashed the filters every few days with no real change. It's not getting any worse, but not getting much better. In the last week, Ph has gone up from 7.5 to 8, CYA has dropped from 60 to 55 with increased sun, and TA is steady at 90. Does the rising pH suggest algae or polllen? Thanks for advice, --Erin
 

Erin R

Bronze Supporter
Mar 14, 2019
22
Tallahassee, FL
Thanks for your quick response! The filter pressure has not changed much over the weeks, holding steady at 18. As for the type of filter, I just went to look and it's a Hayward Pro-Series High Rate Sand Filter, Model # S244T. I'll add it to my signature--thanks for the advice. (Lots more data on the label, but I'm not sure which is relevant.) Does that help diagnose?
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
19,841
Northern NJ
What test kit do you use?

When was your sand last deep cleaned?


 

Erin R

Bronze Supporter
Mar 14, 2019
22
Tallahassee, FL
I use the full Taylor professional chemical test kit. I backwash the filter at least weekly, but I'm not sure when it was last deep cleaned. It was replaced in August of 2016, so it's about four years old. I looked over your instructions for the deep clean, and I'll admit to being intimidated, especially if I break something, as I'm reluctant to go buy parts while on quarantine. Does the fact that the pressure is so low, 18 or so, suggest that the filter may be okay?

Does the image I posted suggest anything to you about whether it's pollen or algae? Does it make a difference if it's the filter?
 

carlos31820

LifeTime Supporter
Nov 22, 2010
413
Midland, Georgia
Going out on a limb but the white steps appear to have what looks like metal staining (iron?). Could that be what's making your pool color look off?

My iron staining tends to make the pool surface look somewhat greenish because of the combination of the tan/brown stain on my blue surface.

Try rubbing a vitamin C tablet on your pool surface to see if it changes/cleans the discoloration. If it does, it's likely to be iron staining.

For example:
59A2E26D-0C91-4953-A3AF-EB814CAB6B03.jpeg
 

Erin R

Bronze Supporter
Mar 14, 2019
22
Tallahassee, FL
Going out on a limb but the white steps appear to have what looks like metal staining (iron?). Could that be what's making your pool color look off?

My iron staining tends to make the pool surface look somewhat greenish because of the combination of the tan/brown stain on my blue surface.

Try rubbing a vitamin C tablet on your pool surface to see if it changes/cleans the discoloration. If it does, it's likely to be iron staining.

For example:
View attachment 153555
Thank you for this good advice, Carlos! It appears my water is green for reasons even beyond the iron staining you noticed, but cleaning the surface with vitamin C (and even a magic eraser) does lift up some of the grime you noticed. Grateful for your help! --Erin
 

Erin R

Bronze Supporter
Mar 14, 2019
22
Tallahassee, FL
Allen, thanks very much for your advice here. It's taken me a few days to reply because (aggravatingly!) I ran out of DPD powder to run the second half of the the overnight chlorine test and had to wait a few days for a new delivery. Now I've run it two days in a row and do not appear to be losing any chlorine overnight. I guess that means I don't have an algae problem, but I'm still baffled as to what is causing the greenish hue and very cloudy water.

During the days I could not complete the overnight chlorine test, I ran the hyperchlorinate setting overnight and boosted my normal SWG percentage, doubling the chlorine level from around 7 to 15, and it is now at around 13. I normally keep my CYA at 60, but I'm having trouble keeping it above 55 the last few days (I see in the SLAM information that I should be aiming for 70), so I'll add more today. TFP says I should SLAM to 24 FC at this CYA, which I didn't get to (or at least didn't sustain), and while the water is still extremely cloudy, it has not gotten any more green, and may even be slightly less green. Here were my levels yesterday:

FC - 13
pH - 7.7
TA - 90
CYA - 55
SALT - 3500
WATER TEMP - 87

Could this have been algae that I resolved, even though I never got to full SLAM level of chlorine? Or could it be something else? Thanks as always, --Erin
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
19,841
Northern NJ
CYA 55 versus 60 can't be measured. We round up. If the dot disappears between 60 and 50 you call it 60.

CYA degrades with higher water temperatures. Read How is CYA Lost and Degrade in Pool Water?

What % do you have your Aquarite set t?

If the green is not from alage then it is from metals in your pool. Iron or copper. Where does your pool fill water come from? Take your pool water to a pools tore and have them test your water for metals. Don't buy whatever they try and push you to.
 

Erin R

Bronze Supporter
Mar 14, 2019
22
Tallahassee, FL
Thanks, Allen, that explains why I'm having trouble with CYA. When the pool first started turning color, I set the Aquarite from about 90 to 100%, and I increased the run time about two hours from six to eight or nine. The chlorine level is staying pretty high at 12-13, but I bought some liquid bleach if you think it's still wise to SLAM to 24.

Carlos had also suggested that the problem may be metals in the pool, and while there could be some metals in the baseline, I don't think that's the main problem here, because my pool fills only with rain water in the summer (it is plentiful here in North Florida). The greenish/cloudiness began when the temperature rose, but not during any huge rain events. I haven't used a hose with municipal water for many months (maybe some in February?).

In the end, I'm wondering if I really did have an algae problem when I first posted, but then I boosted the chlorine level enough to kill it, or most of it, and now I just have a suspension of dead algae? The green color does seem to have gotten a bit better in the week or so since I first posted. There is still a bit of a weird hue, but the cloudiness is the main problem now. It's very bad--there is no more than 1-2 feet of visibility in the water. Could it just be dead algae? Or would that sink to the bottom?

I'm backwashing and rinsing like crazy to clear it, up, and I watched the video on how to deep clean the sand, so maybe that's the next step. Thanks again, --Erin
 

cowboycasey

Gold Supporter
LifeTime Supporter
TFP Guide
Jul 3, 2013
4,328
Fletcher, OK
Take your water to SLAM level and hold there checking every 2 hours until you pass

To finish the SLAM process your pool has to be clear and you SLAM chlorine level must not fall more that 1 FC so you did not pass the SLAM.. Just by raising your FC a little you started to kill the algae that is why it is getting clearer...
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
34,364
Sebring, Florida
As cowboy casey says above.....SLAM the pool! You are over complicating an issue that looks to me like you have algae.....simple....SLAM it and post your test results (current) so we can see where you are starting.

On the left side of your steps the pool walls look quite yellow......what is that?
 

Erin R

Bronze Supporter
Mar 14, 2019
22
Tallahassee, FL
Thanks again to everyone for helping me reclaim my pool from algae! It's taken me a while to complete the process, but I've finally SLAM-cleared the pool and it looks like my picture again. It's now completely clear in color, with only the faintest residue of cloudiness, which I hope to resolve today with another vacuuming. My last question is about how best to allow the chlorine level to normalize to a level that will be safe for people to get back in the water.

During the SLAM, I raised FC to 23-24 (CYA at 55-60) and held it there fairly consistently for about a week, although it always got a bit lower during the height of the day. There is a shortage of chlorinating liquid in town, so I did this by running the SWG at 100% 24 hours a day for a few days and strategically adding the only three gallons of chlorinating liquid (10% bleach) that I could get during the height of the day, when the FC level would drop. Levels varied between 19-24 during the day, and I also had to replenish CYA a fair amount, but I kept levels up as consistently as possible and backwashed the filter frequently.

Once the color was completely clear and the cloudiness all but gone, I ran and passed an overnight FC test (although I had never actually failed one, which was what made diagnosing the problem confusing). By the next day, the FC level was down to about 18, too high for swimming, so I'm letting levels drift down to a safer level and wondering the safest way to do that. In August, I would normally run the SWG for about 6-8 hours at 80-100% depending on levels. Instead, I set it to run at only 50% for 8 hours a day, to see how fast the FC would fall. Turns out, not so fast.

Three days later, FC is at 16, CYA: 55, pH is at 7.6, and TA is stable at 90. I'm wondering if it's safe to turn the SWG off entirely and just operate it like a non-SWG pool until the FC level normalizes, or whether this could invite another algal bloom? Does it matter how fast the FC returns to normal? And by the way, what's the highest FC level you'd allow swimmers in at? I'm always so grateful for the advice I get on this site--thank you in advance! --Erin

P.S. Dave and Carlos both noted the yellowish walls near the stairs and wondered what it is. The truth is that I'm not entirely sure. I can get most of it off by cleaning it with a magic eraser, but while that makes it much better, there is always some staining that I can't remove. Years back, my husband thought it might be mustard algae and he tried to get rid of it as though it were, but nothing much changed. Now my son and I just magic-erase it away periodically. The pool water is mostly rainwater, and very occasional some additional municipal water from the hose, but not recently. High TA, but no metals.
 

cowboycasey

Gold Supporter
LifeTime Supporter
TFP Guide
Jul 3, 2013
4,328
Fletcher, OK
You can swim in your pool up to SLAM levels with no issues... Just turn off your SWG until chlorine drops to normal level and turn it back on :)