Green pool saga, mustard algae, ugh!

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kco82

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Jul 17, 2012
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New to the forums - thank you in advance for the advice!

We are on day 6 of treating the dreaded mustard algae. A little pool background:

40,000 gallon in-ground pool w/ a spa inset.
white plaster
Caretaker system
Triton 2 tr-100 sand filter w/ zeobrite

We started last wednesday, July 11th

Added 4 c Muriatic acid
Waited 1 hr, added 8 lbs Biogaurd Maintain CLC3
Waited 1 hr, added 2 quarts Biogaurd Banish
Soaking all pool toys & equipment

Running filter 24/7

FC spiked @ 30 and has held high throughout treatment

7/14 Added phos-free

7/16 added second heavy dose of Sea Klear

Analysis as of 7/16

Saturation index -0.7
TDS 450
CYA 151
TC 14
FC 14
pH 7.3
TA 95
Adj. TA 50
Total Hardness 149

Copper 0.6

The trouble continues, though we are seeing a bit more water clarity, it is still very green, with patches of brown stuff (which I believe to be the dead algae) on the bottom.

Our pool store is advising us to just let things ride for the next few days, would greatly appreciate a second (or third, fourth, etc) opinion.

Thanks and cheers,

Kathleen
 
Your pool store forgot to tell you that you CYA level is 2x higher than it should be and that means that the chlorine you've got in your pool, even at 30ppm is not enough kill the algae. When CYA is high, draining and refilling is the only answer. You'll need to drain around 70% of your water, which is a lot. It is done in phases though because it is too much water to replace at once.

If you want to take control of this problem and get to swimming, we can help you. But you need to do some work yourself, a little schooling and information for you (read Pool School, many times over), and the willingness to turn a blind ear to the pool store and their solutions. Obviously it doesn't work, and it can get very expensive to buy more products they will undoubtedly try to sell you, that don't work.

Can you tell us why you think it's mustard algae? Does it live in the shady areas of the pool?
 
I do not even know what all that "stuff" you have been putting in your pool is. The only thing you should be putting in the pool is chlorine ... in liquid form ... no fancy names ... just bleach. Although there is no point in adding the bleach until you get your CYA under control and have yourself a good test kit.

There is no reason to EVER have to add things to remove phosphates or any algaecides ... unless you are just trying to keep the pool store in business.
 
frogabog said:
Your pool store forgot to tell you that you CYA level is 2x higher than it should be and that means that the chlorine you've got in your pool, even at 30ppm is not enough kill the algae.
Click to expand...

I am willing to bet the Pool Store employee has no understanding of the relationship between CYA and Chlorine. They know how to run the test computer and ring up the sales at the register. No practical knowledge of pool chemistry and why keeping your CYA below 80 ppm is even needed.
 
We believed it was mustard algae because our pool was a yellow green, with particles attaching to the side and bottom of the pool, the material would puff up when brushing and then settle back down.

on 7/13:
CYA 136
FC 30

on 7/14
CYA 78
FC 16

7/16
CYA 151
FC 14

with regard to what the "stuff" was that we put in:
Maintain = shock
banish = copper algeacide
sea klear = coagulant

I fully believe our pool store is run by goons, we are novices and learning the hard way, this is our first summer of pool ownership, we live in NW washington w/only one pool store in town - they have had us by the short and curlies, which is why we are so happy to have found you!

I have been brushing our pool every few hours to ensure we are filtering the most we can.
 
Are those test results from the pool store? There is no way your CYA changed that much unless you replaced half your water to drop it from 136 to 78ppm and then put a LOT of dichlor/trichlor in the pool to raise it back up to 151ppm.

This just reiterates the need to have your own test kit to have accurate REPEATABLE results.

I still do not know what "shock" is ... is it dichlor or trichlor or cal-hypo. I (we) prefer to use the chemical names (and not product names) as it is clearer what we are adding to the pool.

Adding copper to the pool is a BAD idea ... that is what caused stains and green hair.
Coagulant serves no real purpose unless you are vacuuming it to waste.

Order a test kit.
Read Pool School.
Go through the correct shock PROCESS.
 
It could be regular algae. Mustard algae thrives in shade, as opposed to standard algae. So, if these areas are areas that get sun (I know... not a lot around here but it does come out so you should know if the sun reaches the sides and bottom) I'd say it might not be mustard algae.

That being said, only the amount of chlorine you use to shock the pool makes much difference between the two kinds of algae. Oh, and some extra work cleaning anything that touches pool water. None of the other stuff will help, I'm sorry you got caught by the pool store before you found TFP.

If you want to get this handled, by all means get a decent test kit. When you have your own results available, it's easy for us to hold your hand while dealing with this so you can swim soon. Our season here is short... as you know. Time's a wastin! :~}
 
test kit ordered! in the mean time:

the shock we used was cal-hypo,
we have an automatic chlorinator that we put tri-chlor pucks into every few weeks

we now know we have made grievous pool errors, working on digging ourselves out of this hole, and feeling otherwise bummed and frustrated, appreciative of your patience.

while we wait for our test kit's arrival should I be doing anything about the alkalinity? I am concerned about the corrosiveness of the water.
do you use liquid bleach instead of the pucks? like clorox?
 
Good job on ordering a kit ... it will help tremendously.

Do not worry about TA (that is one of the last things to worry about ... but the one that all newbies worry about first).
Keep the pH in the mid 7s ... this is the largest contributor to the CSI.

Since your CH actually seems to be low, you could continue to use the cal-hypo to maintain your FC levels and raise the CH while waiting for your test kit. Then you will need to switch to bleach after the CYA and CH are in the recommended ranges.

Of course that is AFTER you have replaced around 75% of your water.
 

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Backwash when the psi rises to ~8-10psi above normal working pressure. Backwash till the water runs clear in the sight glass. Then rinse, and return to filter.

I wouldn't worry about chlorine right now. Best to do the drain and refill dance (see pool school) and get the CYA down so you can chlorinate at a reasonable level and kill the algae. It'll take a LOT of chlorine to do it at your CYA level.

Take the pucks out of the chlorinator as well. They will only add more CYA. Save them for vacations.

Once the pool is drained and refilled, CYA is down you'll start with adjusting pH if needed to around 7.2-7.4. Then you can begin the shocking process. Please read pool school and the shocking information there. The clearing a green swamp info is particularly useful.

Edit: What is the surface of your pool? Plaster, or vinyl? If vinyl, don't worry about CH. If you put your pool information into your signature line it'll be helpful for us.
 
frogabog said:
Backwash when the psi rises to ~8-10psi above normal working pressure. Backwash till the water runs clear in the sight glass. Then rinse, and return to filter.
Click to expand...

Excuse this EDIT, but that is no longer the recommendation typically given here.

The latest recommendation is to backwash the filter when the pressure rises 20-25% of the clean pressure.

If your clean pressure is 10psi you should backwash around 12psi .. if you wait for 20 psi (a 100% increase), you will likely have VERY little flow circulating the pool.
 
Ordering the test kit is the first step in never going to the GoonPoolStore. Once you get it, you can test your own water and you can shop at the Wal-Mart and every home improvement or grocery store to get what you NEED to fix your pool and keep it clear and sparkly.

Some of this sounds confusing but it will start making sense once you test your own water and use the BBB methods we all use here.
 
I took a look at all the previous pool store analysis, CYA has hovered @ 140-150 as we have worked to get our pool in shape over the last 2 weeks.

Let me make sure I understand completely what is to be done:

1) backwash my filter for 10 minutes
2) drain 50-75% of my water out of the pool to get my CYA to appropriate levels
3) replace said water
4) test water once I receive the test kit in the mail (eta tomorrow afternoon)
5) adjust pH as needed
6) begin shocking as described by TFP
7) swim!!!!
 
Many people use backwash to irrigate their yard. In some instances you could have something in the pool the grass doesn't like but I think your CL is low enough. You could dump it on your lawn then dilute it by running the sprinklers.
 
You backwash whenever your pressure goes up 20-25% of the clean pressure and you do it long enough for the water to be clear coming out.

Beyond that, your process seems correct. It may take a few drain and refills as any reading of CYA over 100ppm starts to be inaccurate.

You should be able to use the water on your plants without much issue.
 
You can certainly brush the pool. Could use a pressure washer when the water is low.

Adding bleach "might" help hold off the algae (if you keep the water circulating to mix it), but until you are actually following the shock process you will not likely stay ahead of it.
 
Alright - after a few days of emptying & re-filling, we are ready to begin getting rid of the green. water looks MUCH better clarity wise, still green but not soupy/cloudy.

went out and checked levels this morning:

FC 2
TA 120
CYA 50
pH 7.6
CH 70

I bought 4 gallons of 15% chlorine and a bag of sodium bicarb @ the farm supply
 

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