Stubborn Algae Removal

[Agent99]

I opened my pool to the typical green swamp I get after the winter (really need to get a handle on this but it is usually not a big deal...just SLAM and a week later, I'm good).

This season is different. I've SLAM'ed the pool and the water is back to crystal clear BUT I have extremely stubborn (stained?) pool walls/steps. I may be paying dearly for my laziness this year.

I've attached a few pictures but even after pressure washing with my turbo nozzle, the algae remains and honestly seems little disturbed by the pressure washing. Keep in mind I did the pressure washing under the water...not sure if that impacts the effectiveness of pressure washing. I really want to avoid draining my pool (I'm in dry as a bone California) but I don't know.

At this point, I'm not sure what to do. In one of the pictures, you see the algae on my pool cleaner hose. It is rough to the touch and takes quite a bit of fingernail scraping to remove it; a putty knife would be better. This is some seriously tough algae...never encountered the like before.

I think I will keep the chlorine levels at 20+ for a while and see what happens but I'm not bullish on this. I have a feeling more serious mechanical scarification might be on the order. Maybe I could drain the pool below the highest step and pressure wash it to see if makes a difference? Would muriatic acid help?

Thanks for any help you might be.

Cheers,

Chris

 

[tim5055]

You needed to continue the SLAM Process

If there is any visible algae, the water is not clear.

 

[Agent99]

Roger that...I'll keep SLAM'ing.

I was really shocked (then depressed) that my pressure washer didn't touch it. That turbo nozzle can slice through flesh! hahaha

I have some DPD powder on order (had enough for 1 test a couple days ago) so I don't know my exact chlorine levels or have done the OCLT but I'm just going to keep dumping chlorine in and soon I'll have numbers to relay.

Thanks!

 

[mknauss]

i would be curious what happens if you put a trichlor puck on the plaster for a few minutes. Do not let it sit in one spot too long. If it is algae, it should attach it quite rapidly in the spot you apply the puck.

Is the surface of the pool rougher than in the past?

 

[Agent99]

I don't have any pucks handy but it is an interesting idea so maybe I'll get some.

The Pebble Sheen finish is new as of Summer 2015 so I would say no to your question.

 

[mknauss]

OK -- just a thought about calcium scale embedded with algae.

Your CSI can get high on the scaling side in the winter if you CH and TA are already high, you do not test the pH which still climbs, and the water temperature is low.

 

[Agent99]

I think I meet all those parameters! Pool temp is probably in the 60s F and I am pretty darn sure my pH is way up there (always a battle I'm fighting...should buy stock in muriatic acid companies) and therefore my TA is usually up there, too. CYA is likely to be zero (always seems to be upon opening the pool after winter--saw your note about ammonia in another thread) but I haven't measured anything yet since I immediately (albeit prematurely I suppose) started SLAM'ing it. I know I can't measure the pH accurately with so much chlorine in the pool but I assume CYA, TA and CH are still okay to measure in the presence of SLAM'ing? I'll post numbers tonight if so.

 

[mknauss]

You definitely should test the CYA, TA, and CH. You should never just dump chlorine in a pool without knowing the CYA.

Enter all your data in PoolMath and see what the CSI is. Then change your temperature to 60 (I bet your water gets colder than that) and see what your CSI is.

 

[Agent99]

Okay, some numbers:

pH - unknown (high FC)
FC - unknown (out of DPD powder but guess about 20ish)
TA - 260
CH - 180
CYA - 0
Temp - 70 F (warmer than I thought...changing 70-->60 moves CSI to 1.2)
CSI - 1.3 (assuming a pH of 8.6, which is a total guess)

I just dumped in a gallon of 14.5% muriatic acid so I'll begin, once again, the long journey of getting the TA down. (moves pH down 0.6 temporarily and TA down 10)
I'm also adding CYA to the skimmer in a bag.
The hockey puck test (was able to buy a single one from Home Depot) is showing a nice clean (free of algae) circle on a step. Pretty cool. I think this tells me that I need to maintain high chlorine to get rid of this tough algae?

Hmmmm, now that I'm reading about Dichlor, I could've used that as shock since my CYA is zero...kinda get the CYA for free with some added chlorine. Oh well...too late. I'll just keep going with the liquid chlorine.

Need to up the calcium as well but it isn't bad.

Still waiting for the mailman to deliver my DPD powder! Ugh....

 

[mknauss]

I doubt your pH was that high. But that can wait.

The puck test is a success. So SLAM it is. Stay at it. Brush alot. The more you brush the faster it will go.

 

[Agent99]

So here is a shot of the trichlor puck burning right through the algae. I probably had it on there not much longer than 20 minutes.

This also gave me an idea: why not sprinkle some dichlor over my steps and then brush it off after 20-30 minutes?

I put 5 lbs of stabilizer in my skimmer (in a bag) and PoolMath says this will give me a CYA of 24.

I put 5 lbs of dichlor in the pool and PoolMath says this will increase my FC by 13.3 AND CYA by 12. (it is a 10:9 ratio, FC:CYA from dichlor)

So sprinkling another 5 lbs of dichlor will further bump my CYA another 12 to give me 48, which should be fine.

I only wish I'd educated myself about dichlor BEFORE putting the stabilizer in or I could've gotten it for free. Oh well...I'll get another 26.6 of FC out of the 10 lbs of dichlor so that's something.

 

[Agent99]

DPD Powder arrived!

FC is 40! Yikes...way overdid it. I was so shocked by it I forgot to check the CCs! Time to chill on adding more chlorine...back to brushing, brushing, brushing....

 

[Casey]

DPD Powder arrived!

FC is 40! Yikes...way overdid it. I was so shocked by it I forgot to check the CCs! Time to chill on adding more chlorine...back to brushing, brushing, brushing....

I'd say so... take advantage of it and brush the daylight out of that pool!

 

[Agent99]

FC down to 38 overnight. Brushing, brushing, brushing.... My wife thinks the embedded algae looks a touch lighter but I don't know. I'm wondering if I need a bit "tougher" of a brush? This is some mighty tough-skinned/shelled/whatever algae!!!

Anyone think sprinkling dichlor over some of the horizontal surfaces to be a good idea? I know my FC is stupid high so I was going to wait a bit before doing it....

This weekend I will hose down the cartridges real well.

Thanks!

 

[Agent99]

So the OCLT: 31 last night and 28 this morning. OCLT seems to be about 3 ppm drop...two nights in a row now that I can measure it.

I still brush. All the horizontal surfaces (steps) seem to accumulate algae powder constantly. I keep sweeping clouds off of them. Things don't look like they are progressing a whole lot to me. The pumps have been running 7.5 days continuous now.

Today I will give the pumps a breather as I shut down for cartridge cleaning and the 280 is going to be fully scrubbed down and I am going to rebuild it as well.

Fun fun fun..................

 

[RobertScalchi]

Its going to take some time like a week or so to remove the staining at SLAM or SHOCK levels, but it will eventually come out. My corners of my side wall and floor are stained where the leaves fell in over the winter, and the stains are slowly disappearing. If you have a tri chlor puck, try putting it in a d
sock and rubbing the affected area, as some have advocated on here.

 

[Agent99]

FC 23.5
pH --
TA 240
CH 320
CYA ~47
Temp 61 F

I've been adding muriatic acid a little bit at a time daily to knock the TA down.
I added calcium chloride to increase the CH.
Yesterday I cleaned the cartridges and then soaked them in a heavy chlorine solution for a few hours.
The CYA is much higher than expected from calculations. I was expecting about 36 and I have about 10 points higher.
It is making me wonder if my 25k gallons is higher than what I have.

I still continue to brush but I'm thinking I need a stiffer, tougher brush to really dig in.
Sprinkling dichlor on the steps is still on my mind but now my CYA is at the high side of the accepted range. Ugh!

 

[mknauss]

Round up your CYA to 50. The scale on the test vial is logarithmic, so you cannot read a '47'.

You can buy a stainless steel brush. Be careful how aggressive you get with it.

 

[Agent99]

I put a logarithmic scale on my vial so as a matter of fact, I *can* read a 47.

Funny, I went to Amazon to look at stiff brushes and found a couple that looked good and ordered them. They will be here this evening! WOW!

 

[Agent99]

Finally brushing feels like I'm actually doing something now. I have some algae clouds coming off the walls and floor with the bristle pool brushes.

I ordered a 10" and 18". The 10" is nice for the steps and spa as I can get into corners better and scrub a little more vigorously.

The 18" is nice for the walls and floor but it is much tougher to push. I really got a workout brushing the pool this evening!

I ordered these brushes this morning from Amazon...arrived at 7:40 PM PST. Gotta love Amazon Prime!