Mustard Algae questions

[Kidneydoc]

Long time BBB / TFP reader and believer. I am in central florida (Vero Beach)...12,000g pool, SWG
I think I have mustard algae. I keep my SWG pool FC between 5-10, but recent mega rain and deck runoff likely pushed up phos levels in my pool + I have been lazy this winter and did not brush the sides of the pool in a long time (...a year). I have automatic pool cleaner, so bottom of pool and bottom of the walls look fine. I went in the pool last week and noticed a haze over the side of the walls. Water was clear, but I saw a puff of "powder" come off the wall with brushing. From a distance, you can see a green/yellow patchy discoloration over parts of the walls.

I started the SLAM 5 days ago. FC levels 45-50 with pump running 24/7 for about 5 days now. I have been brushing with pole brush every day, cleaned filter every 2 days or so, and used Lanthium (PhosFree) to get phos down to 0 (....was 300-600).

However, minimal change in color on walls. I went into pool this AM, and pulled out the lights and cleaned the niches....there was "powder" in there...I suspect algae was camped out there as well.

I have to use a hand brush and scrub, scrub, scrub and then yellow color does come off the wall.

Questions-
-It will take me a few days to hand scrub the pool walls....do I keep the SLAM going the whole time with pump running 24/7...with FC 45- 50? (....my CYA is about 70)
-As much as I scrub, can I really get all of it off?
-As soon as the FC drops to normal levels, will it all just come back?
-is pH test and CYA test (TFT kit) still accurate with FC40+ range
-Any risk using the pool with FC 40-50 level?

Any input appreciated! Thanks.

 

[mknauss]

You should not be maintaining mustard level FC. The protocol is to run a normal SLAM then raise to mustard level FC for 24 hours.
Pool School - Mustard Algae

CYA test is valid at high FC. pH is NOT valid at FC above 10ppm.

You should not enter the pool when your FC is above SLAM level. For a CYA of 70 that is 28 ppm FC.

You did the PhosFree stuff. OK. Probably not necessary. But now in your Cartridge filter (it works like a clarifier). Have you cleaned your filters? With TSP?

Please read the Pool School article again.

Take care.

 

[Catanzaro]

Kidneydoc:

Is it at all possible that you do not have mustard algae on your walls, but the plaster has discolored and what you are seeing are reflections and the mustard algae has been taken care of. For the first time in years I allowed my levels to drop because I am still dialing in my SWG, (instead of liquid), shut off my filter because temperatures were low, etc. The white steps appeared to be greenish/yellow. I quickly dove down with goggles and a magic eraser. There was nothing there. Within 30 minutes the color changed back as the sun had shifted. My algae was in the deep end where the liner meets the base wall.

From your picture, it looks like you are at the stage in where the algae has been killed off and now the last few days to a week are need to go from green/yellow to cloudy to clear. In addition, how is your circulation in the pool? If you have good circulation and your pool is following the proper CYA/FC levels and you do not allow them to fall, there is a very slight chance that you can get algae, unless there are other underlying reasons. In addition, phosphates levels of 300-600 do not justify adding any extra chemicals, no matter what claims the pool stores make. In very rare circumstances, when all else has failed, do phosphate removers come into play.

Good luck and keep us posted!

 

[Kidneydoc]

Thanks all!

-I did normal SLAM first X 48 hrs, then pushed FC up to MA levels
-I pulled out the light fixtures and there was algae in the niche cans, and I am keeping light fixtures out of the cans/niche for now. Not sure if I want to mess with changing gaskets just yet...
-A wire brush to the walls definitely has the "puff" of algae and the green/yellow color clears with enough scrubbing...but there is a lot of surface area to scrub
-I have been cleaning the filter every 48 hours...but just hosing it down...no cleaning agent


The problem is I am not sure I can scrub every inch of the walls, etc to really remove all the algae

I have read may posts about the downside of Na-Bromide....but what If I used it, kill the algae quickly, then drain much of the pool and start over with usual chlorine?

Also, I could just drain 1/2 the pool/refill now, get the CYA level to 20-30, and then I will need less bleach to keep FC at MA levels...

Thanks for everyone's help!

 

[Kidneydoc]

Update-

I am draining pool to get CYA down to 20-30 range.

I am able to get the algae of the walls with the wire brush....nylon brush appears useless in this situation.

I am holding off any bromide at this time....will try SLAM-MA for now.

High FC and brush, clean filter, brush, clean filter, and repeat until walls clear and no overnight FC drop

Need

 

[Kidneydoc]

Lights have been removed from niches...main light on pool deck, spa light on floor of spa.

I am going to change gaskets as well.

Can a wire brush hurt the gemcoat/gunnite?

The color is better, but there is still a puff of grey? Powder that comes off the walls EVERYWHERE and the pool does cloud up after i brush and the filter pressure goes up a few psi...then i look a filter a few hours later and there is a yellow /grey deposits i have to wash out.

I guess this is a real mustard algae issue....unless the wire brush can do something to the gemcoat (? Can it....i dont think so...)

I will keep brushing and SLAM-MA levelels for a few? Weeks with continued brushing....

Any other thoughts
welcome....

 

[Catanzaro]

Kidneydoc:

I would have the plaster inspected. Puff of yellow and gray. It is possible that the pigmentation in the plaster is begin caught in the filter, along with pollen, etc. It is like when I pressure wash my driveway with force to clean every few years. There is sand at the end of the driveway after water runs off. Maybe with the color of the plaster (which I believe has sand in it, this is what you are seeing). Again, was mentioned before, your plaster and water appear to be fine from the pictures.

 

[Kidneydoc]

Thanks for input. Pool is close ton15 yrs old....i have owned house for past 5 yrs.

I will get it looked at asap.

Also, overnight TC drop is minimal....1 at most....so i think i have killed algae ( if i actually had any to kill)

Thanks again....very fustrating issue....all your help is greatly appreciated!

 

[Kidneydoc]

Thanks for input. Pool is close ton15 yrs old....i have owned house for past 5 yrs.

I will get it looked at asap.

Also, overnight TC drop is minimal....1 at most....so i think i have killed algae ( if i actually had any to kill)

Thanks again....very fustrating issue....all your help is greatly appreciated!

 

[Kidneydoc]

I think I have calcium scale. I checked some local pool cleaners and they led me down this path. See new pics.
I am not sure if I will do anything about it, but I am pretty sure it is not algae.
I have always let my TA stay around 40-50 with the SWG...but looking at the CSI calculations, it looks like I should keep my TA closer to 100 (...my CH is now at 250 with all the water exchanging I have done)....I guess time to stock up on bicarb

Any other thoughts?

 

[mknauss]

It could be calcium scale, but from the past. With what you just posted on CH and TA, your CSI is most likely negative.

If it is calcium scale, then keeping your CSI negative, near -0.6, would possibly dissolve some of the scale and put it back in solution.

Do you have past data to see what your CSI was in the past?

 

[Kidneydoc]

Usual average values for past 4-5 yrs (pool built in 2006....I have no idea how pool kept up until 2013)

FC 5-10
pH 7.6
TA=40
CH=300
CYA=80
Salt=3400
Borate=30
temp=84
CSI= -1.02 .....so this would put me in the problem area for 5 yrs....? cause of scale issue

Now, if I keep all the above the same, except drop CYA down to 60 and push TA up to 80, I get a CSI of -0.24. Much better.

So perhaps this is a reasonable set up. I already have the CYA down to 30 (using bleach for now (but will turn on SWG when TC drops ) as I did several 1/3 cycles of drain/fill). So it would be easy to slowly raise the CYA to 60 and the bicarb requirements would also be reasonable to keep it at 80 instead of 40ish.

Sound good?

 

[mknauss]

Read Pool School - Calcium Saturation Index (CSI))

Water with a CSI less than -0.6 is aggressive and over time, can deplete your plaster of calcium and cause it to fail.

If anything, the dust you see is your plaster dissolving, if those numbers you show have been that way for a long time.

I would suggest getting your TA up to 70 with baking soda.