Possible algae but no OCLT drop

[scar4ace]

Hi all,

Greatest appreciation for all the knowledge and insight here.

Have a qst - Is it possible to have active algae with no overnight drop of FCL levels?

Attached some pics, does seem to be spreading , maybe I have some cl resistant form of algae? Or maybe it's just sand, I'm looking to replace my really old sand filter .

This keeps happening to my pool, I do believe SLAM makes it better but I can't keep this algae away. The way it spreads and the green ness on steps I am certain it's algae.

Also clusters of spots on wall (had a pool guy out once and he said it wasn't algae or even black algae but wasn't sure what it was) the last 2 pics shows the spots zoomed in and from distance.

My readings incl fas-dpd for chlorine:

After sunset last night
FCL - 3.5ppm
CCL - 0.5ppm
pH - 7.8 (High - adding dry acid today)
TA - 150ppm
CH - 175ppm
CYA - 30

Before sunrise this morning
FCL - 3.5ppm!
CCL- 0ppm!

Any advice. Planning to run yet another SLAM after doing one late November.

 

[Newdude]

possible to have active algae with no overnight drop of FCL levels?

No. Is it pollen season for you ? Any farms or open fields of dirt nearby ? Neither of those will affect the chemistry by much but will look very similar to algae.

 

[Texas Splash]

I'll offer my thoughts as well:
- Much too much debris in the pool. First step must be to scoop, brush, and vacuum all debris to clear the surfaces.
- How are you testing? Your signature shows various test strips and a DPD? Are you using products from Clear Choice Labs?
- Staining appears evident. Perhaps organics embedded into the plaster.
- Painted surfaces are not only questionable for longevity, but could also be confusing surface discoloration in the pics.
- If you've had algae for a long time, some of it could be embedded in the old plaster. You might also have Mustard Algae which requires a specific protocol to completely remove.
- Your CH level is low for a plaster pool. If that number is accurate and it's been that way for a long time, your plaster may be eroding/pitting which makes algae control even more difficult.
- Remember dry acid adds sulfates which can be problematic over time to the pool and SWG. Try to stick to muriatic acid if possible.

Hope some of these notes gives you some things to make positive progress on. Good luck!

 

[scar4ace]

No. Is it pollen season for you ? Any farms or open fields of dirt nearby ? Neither of those will affect the chemistry by much but will look very similar to algae.

It is pollen season here on the Eastern coast Australia, no farms/dirt fields near by. Will run another OCLT just to confirm.
So all forms of live/active algae should lower the FCL level overnight? Could this be dead algae maybe.

I'll offer my thoughts as well:
- Much too much debris in the pool. First step must be to scoop, brush, and vacuum all debris to clear the surfaces.
- How are you testing? Your signature shows various test strips and a DPD? Are you using products from Clear Choice Labs?
- Staining appears evident. Perhaps organics embedded into the plaster.
- Painted surfaces are not only questionable for longevity, but could also be confusing surface discoloration in the pics.
- If you've had algae for a long time, some of it could be embedded in the old plaster. You might also have Mustard Algae which requires a specific protocol to completely remove.
- Your CH level is low for a plaster pool. If that number is accurate and it's been that way for a long time, your plaster may be eroding/pitting which makes algae control even more difficult.
- Remember dry acid adds sulfates which can be problematic over time to the pool and SWG. Try to stick to muriatic acid if possible.

Hope some of these notes gives you some things to make positive progress on. Good luck!

Thanks,
- yes lots of leaves and with the possible algae bloom, I've been hesitant to run the robot cleaner. Will do a good clean and brush before starting SLAM.
- Signature was out of date, apologies. yes Clear Choice Labs all the way, fas-dpd. no more guess strips for me
- Staining: yes I suspect poor quality Salt from local HW chain. Planning to attack this once I get this algae(?) issue sorted. Found a company that advertise they can do this without a drain/acid wash
- CH level yes , and it was even lower sadly, I think this has contributed to a lot of my issues. However my SWCG cell went bust recently and got it expensively replaced. they advised high CH is not ideal for the cell? I understand for concrete pools recommended is at least 250 CH
- I am not 100% sure but I do think I have etching or eroding/pitting of the plaster - there are a few spots where its come off. Will take pics.
- noted re dry acid, thx
- how do I confirm Mustard algae. Given all these issues above, should I still not have a loss in FCL levels overnight if active algae?


I might have let the pool maintenance issues got the better of me, and may need to look into a drain , acid wash , re paint/plaster I suspect? Plaster has come off - coin-size - 3-4 spots around the pool - mainly steps, but the cluster of spots on pool wall, im worried about.

 

[Texas Splash]

how do I confirm Mustard algae. Given all these issues above, should I still not have a loss in FCL levels overnight if active algae?

If you have MA, the initial treatment is a regular SLAM Process first, followed by an elevated (MA) FC level for 24 hrs only. This illustrates that while someone can initially pass all 3 regular SLAM criteria, which includes the OCLT, MA spores can still be present until the 24 treatment is completed. In your situation there may be more to the story (i.e. embedded algae, staining, etc), so just try to take it one step at a time. Do the best you can. Good to hear you have a good test kit.

Mustard Algae

Today We are going to show you how you can get rid of mustard algae in your pool. By following the steps in this guide and with no expensive chemicals.

www.troublefreepool.com

 

[mgtfp]

Looking at your photos, especially this one:



Looks to me like you might have some nice biofilm there. Is this stuff that is flaking off in sheets some sort of slimy mess? Algae (and also potentially some nasty bacteria) can survive in there, protected to a certain degree from chlorine attack (and therefore creating no or little overnight chlorine loss).

You need to get rid of that. If it comes of easily enough, I'd just vacuum that stuff to waste. And keep brushing, brushing and brushing. Very important part of a SLAM to break up biofilm and make algae accessible to chlorine.

How is your overnight chlorine loss at higher FC levels? Reaction rates are proportional to the FC level. At low FC, reaction rates through that biofilm might be too slow to create noticeable loss over night. At higher FC, especially in combination with brushing, it might be a different game.

 

[scar4ace]

How is your overnight chlorine loss at higher FC levels? Reaction rates are proportional to the FC level.

Ah yes that sounds reasonable mate. Will check out tonight , looks like I'm gonna have a busy Xmas

Looks to me like you might have some nice biofilm there. Is this stuff that is flaking off in sheets some sort of slimy mess?

Ah no that's just a bad reflection, there isn't any sort of visible film or material coating etc in pool. Other than the stains on wall

 

[mgtfp]

Ah, now I can see it. Playing tricks with my eyes...

 

[scar4ace]

Hey all,

Started the SLAM on friday with CYA 30.

After a clean and thorough steel brush, the pool turned a deep green, unable to see floor... Not sure if this color confirms that algae is lurking? Or just due to suspended particles regardless of what they are.



Fri night into Sat morning OCLT again no major drop in FC level

Fri night 10pm
FC - 20ppm
CC - 0.5ppm

Sat morn 5.30am
FC-19ppm
Cc-0.5ppm

Another thorough brush today SAT
, still cannot see floor so haven't started vacuum. Added 2 X 5L chlorine today.

Sat night
FC-23.5ppm will see how this goes.

Appreciate any thoughts. And Merry Christmas to all! Stay safe, well and enjoy.

 

[Texas Splash]

After a 100% refill the water should look much better. Are you on a well in your area? Have you tried placing some paper towels or an old white t-shirt in the skimmer to see if it changes orange/brown from iron?

 

[setsailsoon]

That looks like a nasty algae bloom to me that got worse not better... but your OCLT indicates if it's algae it's all dead. Kind of makes me suspect your OCLT test is not working or not being done right. Can you provide details on how you did this? Have you ever added algaecide? Also looks like pools that were SLA'd and not SLAM'd. If you don't Maintain the FC level SLA's don't work.

Chris

 

[mgtfp]

Either algae or metals. What happens when you rub a vitamin C tablet against those stains on the walls?

 

[scar4ace]

Thank you for your replies despite the festivities

Overnight OCLT again seemed ok.

Sat night 10.30pm
FCL - 23.5 ppm (soft was quite close to 23ppm)
CCL - 0.5ppm

Sun morning 5.30am
FCL 22ppm
CCL - 0.5ppm

Are you on a well in your area? Have you tried placing some paper towels or an old white t-shirt in the skimmer to see if it changes orange/brown from iron?

No well. Pic added below. It stained pretty quick within 15 mins. Below is after an hour.

Have you ever added algaecide? Also looks like pools that were SLA'd and not SLAM'd

Yes. Benzalkonium Chloride 150g/L.
Pool guy actually did when they came out to treat algae last summer. (Dec/Jan in Aus). I've used some too since in the thought that while it's not part of SLAM it wouldn't hurt to contain algae as I seem to not get it under control.

Re SLA , previously yes, but this time around I've been testing at least 4 times a day, added 10L chlorine yesterday to maintain , added some again this morning to top up.

It's 30-35c here (86-95 F) so levels dropped by around 7ppm by mid day.

What happens when you rub a vitamin C tablet against those stains

Similar to the paper towel test for metals or Iron? Haven't got any at hand but will get some and test, could use the rest - may as well get some nutritional benefit after the mental stress

So based on the OCLT results am I Ok to stop SLAM and consider metals/Iron + dead algae being the source of troubles?

Usually on day 3 of SLAM I'd expect by now the pool would be turning Blue/clearing up which hasnt happened this time around.

The material is settling on the steps/floor which prob contributes to the colour? See below when I wipe away a little from the step.



Doing a full brush/vacuum today.

Thanks again and happy holidays.

 

[scar4ace]

but your OCLT indicates if it's algae it's all dead. Kind of makes me suspect your OCLT test is not working or not being done right. Can you provide details on how you did this?

Droppy droppy from bottle?

Hehe okay so I use fas-dpd kit from clear choice labs and test as per their instructions, sample arm deep from pool deep end
Rinse tubes in pool water, fill, use magnetic stirrer, evening test and add chlorine around sunset if top up needed, then test at least hour after adding, log this as night result, and then morning before sunrise. SWCG is off during SLAM, pump 24/7 on.

One thing - the sand filter is running in re circulate mode. Should it be on filter mode during SLAM? Also my filter is pretty aged and at times I'm not sure if the deposit is sand from the filter. I need to get it replaced.

also pH readings are high during SLAM but this is expected as they are unreliable correct. Do I need to add some acid due to the high chlorine addition? (separate times of course)

I have some muriatic acid now. Much cheaper than the dry stuff!

 

[scar4ace]

Re iron/metals and staining,.forgot to add this is what my salt cell housing looks like, brown stains...


when I replaced my cell couple months ago the manufacturer suspected the staining is due to impurities in salt. I used the salt from the local hardware chain, never noticed staining before.

 

[Texas Splash]

I am also interested in the results you find after trying Vitamin C tablets on stained areas. Lots of signals pointing to iron.

 

[mgtfp]

Did you lower pH before adding chlorine to SLAM-level? pH was 7.8 at FC 3.5. Going from there to above 20ppm would have brought pH well beyond 8. The combination of high pH with high FC probably triggered iron to fall out of solution.

If you have some distilled water, then you can make a 50:50 dilution with a pool water sample and test the pH of that. The dilution will half the FC, but have no real impact on pH because distilled water has no Alkalinity, but the pool water has. But it's important that it's distilled or deionized water, tap water doesn't work.

Let your FC come down to 20, then do the dilution pH test. Then add acid until pH is below 8. Don't take it it down too low, pH will drop once FC goes down to normal (the complete chlorination cycle is pH neutral - increasing FC with bleach or an SWG increases pH, "using" FC decreases pH).

 

[scar4ace]

Did you lower pH before adding chlorine to SLAM-level? pH was 7.8 at FC 3.5.

I did , added 750g dry acid (didn't have muriatic at the time) however it only reported around 7.4-7.6 when I started the SLAM.

Will do the dilution pH test thanks. Will keep SLAM going , pool looking better after brush/vacuum today.

Switched filter from RECIRCULATE to FILTER now. Assuming most algae dead and vacuum to waste today.

 

[scar4ace]

I have 3 little pairs of eyes staring at me since yesterday, esp given the 35c heat in Sydney. Suffice to say I'm not very popular at home rn. Hope this works in a day or 2 ,

 

[mgtfp]

As long as you can see the bottom, there is no reason why the pool can't be used. Up to SLAM-FC is safe to swim in.

Might need a bit more chlorine to compensate bather load. But hey, it's Christmas.