Can't Get Rid of Algae

[matthewnadeau]

We have an in-ground pool which is about 7 years old. It's about 15,000 gallons with a Pebble Tech surface. I have had very few problems over the years with algae, but since Spring I've really had a problem getting control of it. We live in Northern California where it regularly reaches 90 - 100 deg and I've been keeping our chlorine level up over 5ppm and shocking the pool about every two weeks, but the algae keeps coming back. We brush the side of the pool, super-chlorinate, etc. but nothing has worked so far.

The only difference that I can think of compared to prior years is that I recently changed out our pool cleaner. We had a Hayward Navigator and I changed to Hayward Pool Vac Ultra (right about the time that we started to have the algae problem). Based on the cleaners instructions, I reduced our clean time from 5 hours with the old Navigator down to 2.5 hours with the new cleaner. I assumed that the shorter clean time may be contributing to the algae problem so I increased it to 4 hours per day last week, but the algae came back strong this week.

My typical water balance treatment is:

3 Cl tabs in the skimmer basket
Shock every 2 - 3 weeks
Check pH and Alkilinity every couple of weeks with acid addition about every 2 months and baking soda addition about every 3 - 4 months.

Other than that, our water tends to be pretty stable.

Any ideas on how to get control of the algae?

[doggie]

You probably won't get many replies until you accurately test your CYA and post the results, especially when you use the tabs. :)

[JohnT]

I've been keeping our chlorine level up over 5ppm and shocking the pool about every two weeks, but the algae keeps coming back. We brush the side of the pool, super-chlorinate, etc. but nothing has worked so far.



You are using tablets, so your CYA is probably out of sight. This requires much higher chlorine levels, which you can see at the top of the Chlorine forum. Running at 5ppm won't do anything to get rid of the algae, nor will shocking every two weeks. You have to shock the pool, probably raising the chlorine to at least 20ppm, and keep it there for several days. This will require testing the water several times a day, and adding more chlorine almost every time you test.

Get some good test results, particularly for CYA to get specific advice.

[eckardsl]

We have an in-ground pool which is about 7 years old. It's about 15,000 gallons with a Pebble Tech surface. I have had very few problems over the years with algae, but since Spring I've really had a problem getting control of it. We live in Northern California where it regularly reaches 90 - 100 deg and I've been keeping our chlorine level up over 5ppm and shocking the pool about every two weeks, but the algae keeps coming back. We brush the side of the pool, super-chlorinate, etc. but nothing has worked so far.

The only difference that I can think of compared to prior years is that I recently changed out our pool cleaner. We had a Hayward Navigator and I changed to Hayward Pool Vac Ultra (right about the time that we started to have the algae problem). Based on the cleaners instructions, I reduced our clean time from 5 hours with the old Navigator down to 2.5 hours with the new cleaner. I assumed that the shorter clean time may be contributing to the algae problem so I increased it to 4 hours per day last week, but the algae came back strong this week.

My typical water balance treatment is:

3 Cl tabs in the skimmer basket
Shock every 2 - 3 weeks
Check pH and Alkilinity every couple of weeks with acid addition about every 2 months and baking soda addition about every 3 - 4 months.

Other than that, our water tends to be pretty stable.

Any ideas on how to get control of the algae?

It seems people forget to mention mustard algae. You dump chlorine all day and you won't get rid of it. You need polyquat60 which you can buy at Walmart. Put a whole bottle in and keep brushing and backwashing.

[eckardsl]

There is no test that I know of for mustard algae, but I have had it and nothing will get rid of it except polyquat. Get the 60 per cent at Walmart and dump the whole bottle.

[chem geek]

See this post (http://www.poolforum.com/pf2/showthread.php?p=49822&posted=1#post49822) for more info (and the links to other threads mentioned in it). If your CYA level is higher than 50 ppm, then you will likely just want to do a partial drain/refill since battling the algae with high CYA will be very hard and you'll want to lower your CYA level anyway so you might as well do the dilution of water to lower CYA levels first.

Richard

[Sprocket]

tabs :(

Do you "shock" your pool , or use shock product .

Really not the same thing when you read up more on this bb board .

Get your CYA down to 30 - 40 readings and you'll be a alot happer . Read up on my experiance . Just look for my name using the "search" function .

[matthewnadeau]

I had my water tested and the CYA was 60ppm. Everything else was fine except the alkilinity was a little low. The guy at Leslie's recommended shocking with a non-chlorine shock treatment (Fresh and Clear Chlorine-Free Oxidizer). This is actually what I typically use to "shock" my pool. He didn't seem to thing that Polyquat would do any good. He also suggested increasing my cleaning time to 6 hours.

[heymom1]

How long do you run your filter pump? I've had algae over the last week, got rid of any visible sign of it on Sunday but have been running the pump 24/7 since then. It's not the cleaner that will get rid of algae, it's bleach. Keep your free chlorine levels high - like 10 ppm - and keep brushing every day. After you haven't seen any algae for a week, then clean out your filter cartridges or backwash. If you have a vacuum, I have read many times on this forum that you should "vacuum to waste," whatever that means. I guess it means you vacuum out all the gunk and dump it in someplace away from the pool...

Your CYA level isn't terribly high. Mine is running around 90 right now. When I get back from this summer's trips I am going to take some water out and start using the bleach method.

There's a lot of algae this year, I think it's in the air.

Oh, and you are right about the Polyquat - it's not for treatment of algae, it's for prevention. Ignore that recommendation. Even some pool stores don't sell it to you if you already have algae.

[ChuckD]

Sorry to whomever posted this advice. Poly will prevent the algae, not clear it out.

You need to measure both Combined Cloramines (CC) and Free Clorine (FC). Added together they equal your Total Clorine (TC). When your CC comes down to less than .5 you've eradicated the algae. Stick with just clorine (Chlorox, or the 12.5% you can get at many pool stores) and avoid the other branded "shocking" treatments.

You also need to run your filter 24/7 during this time.
And vacuuming to waste is simply diverting the water sucked up by the vacuum out from the pool system (on to the lawn, or whatever) to save stress on your filter. Some filter systems (like my Hayward EC65) don't have this option.

[heymom1]

See what a quick study I am? :) Only been back a little over a week and already I'm chiming in to tell people what not to do!

[Sprocket]

You got it Mom <S> to you .

It's all downhill and free sailing from now on .

WTG
spro

[Spensar]

I had my water tested and the CYA was 60ppm. Everything else was fine except the alkilinity was a little low. The guy at Leslie's recommended shocking with a non-chlorine shock treatment (Fresh and Clear Chlorine-Free Oxidizer). This is actually what I typically use to "shock" my pool. He didn't seem to thing that Polyquat would do any good. He also suggested increasing my cleaning time to 6 hours.

Between that and your other posts I can see why the algae is persisting. 15,000 gallon pool, CYA at 60 ppm (on the high side), puck in basket chlorination, and maintenance shocking versus algae eradication shock treatment.

This forum has been provided me with tremendous assistance and I'll try to outline the basics, which uou can also find this is many threads. This is the basic process I've been successful with after following advice here when I opened to a nice green pool this spring.

References to adding chlorine is with liquid chlorine - ie. Sodium Hypochlorite. This is sold at pool stores as Pool Chlorine and is usually about a 10% concentrate. Sodium Hypochlorite is also sold as bleach everywhere else and is exactly the same as pool chlorine, the only difference is the concentration is 5.25% (standard) to 6% (Ultra, etc.) You need to read the bottle to check the strength. My pool has been crystal clear for 3 years with Walmarts generic bleach. Just be sure to only buy the regular bleach and not any product with additives for smell, etc.

FIRST STEP - KILL THE ALGAE

This requires bringing you chlorine up to shock levels and keeping it there until the algae is dead and the water is cleared up. Thoroughly brush your pool to loosen the algae, and run your pump 24/7 while in kill mode. That keeps things stirred up, helps filter out the dead algae and also kills the live algae inside your filter and system.

With 60ppm CYA your shock level is approximately 20 ppm of chlorine, which would take 3 gallons of 10% liquid chlorine or 6 gallons of 5.25% bleach to achieve. Add the chlorine slowly in the deep end where the water circulates well.

You will need to add chlorine at least once a day to keep that 20 ppm level up because the chlorine is "used up" killing the algae. If you have a test kit it likely doesn't test the chlorine up to that level, but you can at least make sure you haven't zeroed out. If in doubt, add chlorine. The worst thing you can do is back off the chlorine to early because the algae will bounce right back.

You will likely be able to visibly see if the algae is dead, but as ChuckD said, check that the combined chlorine is almost zero.

If you go in to the pool store for a chlorine reading, hum or block your ears, get the reading for you own use and get out of Dodge without letting them confuse you or sell you product you didn't go in there for. Just say thanks, I have some of that at home and keep moving. Most pool store staff don't know that bleach is Sodium Hypochlorite - save yourself grief and tell them you are using liquid chlorine!

The shock level came from a sticked thread with a chloine/stabilizer level table at http://www.poolforum.com/pf2/showthread.php?t=365

Stabilizer . . . . . . Min. FC . . . . Max FC . . . 'Shock' FC
=> 60 - 90 ppm . . . . 5 ppm . . . . . 10 ppm . . .. 20 ppm

If you replace some water as posted here, the CYA will go down and you can do this before attacking the algae. A new CYA reading can be obtained and the the shock levels adjusted accordingly. Pool store readings are not bullet proof, I've gotten zero CYA readings when I knew it was around 20, so if there is another pool store handy perhaps a double check wouldn't hurt.


The amount of bleach/liquid chlorine is from the slick Bleachcalc program from this thread:
http://www.poolforum.com/pf2/showthread.php?t=4735

You can calculate how much bleach or liquid chlorine is required for your pool volume to get the target chlorine level.


STEP TWO - CLEAN UP

After the algae has been killed you have dead organic matter in your pool. This may show up as lots of fine particles on the bottom and your water may appear cloudy or whiteish.

With my green pool this spring, there was a lot of dead algae to clean up. I would stop the pump for a few hours and let it settle on the bottom and vacummed to waste to get rid of it and not load up my filter. This uses some water but with your high CYA level, that's not a bad thing. Other than that, keep running the pump 24/7 and brush the pool well. You can keep your pool cleaner going as well.

I don't know what kind of filter you have, ours is sand so we just backwash to clear it out. If you have a filter cartridge, posts I have seen suggest it may clog up pretty quick and need to be washed out a lot, so watch for that.

The killing and cleaning process can take several days and you need to be patient. In my case I chlorine bombed the heck out of it and killed it all in a day and a half, and the water cleared over the next three. That was in cold conditions, a liner pool, and different neck of the woods so you experience may be different.


STEP THREE - BALANCE THE WATER AND MAINTAIN

After the algae situation is cleared up the best thing to do is get a complete read of your chlorine, PH, CYA, Alkalinity, etc., and NOT buy anything from the pool store! Post up your numbers to the forum and you can get some advice on balancing the water.

You also should get at least a cheap basic drops kit that measures chlorine and PH. That way you can keep an eye on the chlorine every day or 2 and make sure it doesn't get low which is the gateway for algae to grow back. My golden rule is to not let the chlorine go to less than the minimum level (per the chart). If you do that algae will not be a problem. You need to keep the basic PH, CYA and alkalinity balanced but it it won't matter if the chlorine goes to low and your pool isn't sanitized. If nothing else, keep a eye on the chlorine.

I like the liquid chlorine as there are no additives and I control what goes in the pool. You can still use pucks but be aware that have CYA added in and will raise the level. You will need to check the current CYA levels every once in a while and either adjust the amount of chlorine or swap out some water since CYA does not break down by itself during the season. Pucks aren't evil, you just have to know what's going on with your water.

Good Luck, it really is easy to handle.

[CarlD]

OK: Up to your back bumpers in alligators: Not time to drain the swamp!

1) I don't know what your pH is but you should get it no higher than 7.6. Don't go lower than 7.0, but chlorine is more effective at lower pH levels.

2) Add bleach or liquid chlorine (same thing, different bottle) until your Free Chlorine level (FC) is 20 ppm (parts per million). Test your water 3 times a day and raise FC back to 20 when it's lower, like 15 or less. Plan to do this until your pool sparkles.

3) Run your pump 24/7 until it's clean.

4) Vacuum and brush your pool EVERY SINGLE DAY until it's clear. Vacuum to waste.

5) Be Patient and Persistant.

Now on to draining the Swamp:

You need a good test kit--Taylor K-2006, K-2006C or Leslies On-Line FAS-DPD Chlorine Service Test Kit. In a pinch you can use the WalMart HTH 5-Way Drop test kit--search our site for the Shotglass method to measure chlorine above 5ppm.

Once your pool is clear, plan on testing Chlorine and pH every day the pool is open. Check the other stuff, T/A, CYA and CH once a week. Keep a log of your weekly measures.

When something is out of range, add what you need to fix it ASAP.

Use the B-B-B method of chemicals. Lots of fancy pool store chems are a waste of $$$. You CAN use pucks, but watch your CYA and pH as it pushes CYA up and pH down. But instead you can chlorinate with bleach forever--tho the pool store guys will give you a song'n'dance as to why it's bad!:mad:

It's really very simple, easy and cheap to keep your pool clean all summer. Shocking isn't necessary if you test your water everyday and add bleach as needed, as long as Free Chlorine doesn't drop below the recommended range (for you, that's 5-10ppm ).

Finally: PolyQuat.

Polyquat's great stuff--it's the only algaecide we recommend and it is the only flocculant you need as well. Adding a couple of ounces every week will keep algae at bay if your chlorine level drops too far. It doesn't cause foaming and it's not dangerous.

But...it's an algae preventer, not killer. Only lots and lots of chlorine and brushing kills algae. Also polyquat will cause your chlorine level to drop, so watch that too. I like the stuff and use it, but I know what it does and doesn't do.

Then again, in 5 years with this pool I have only had one minor algae bloom and I raised my FC up to 15ppm, kept it there for 24 hours, ran my pump 24/7 at full speed and it was gone. I caught it early but I got a little lazy which was why it started--my own darn fault for not following my own advice!:D

[CTIGuy]

Up to what chlorine level is safe for bathers?

[CarlD]

Up to what chlorine level is safe for bathers?

The answer is, again dependent on your CYA level. Usually bathers are safe up to the shock level, but I prefer to let FC come down to at least close to the upper end of the maintenance level specified in the Best Guess table.

So when my CYA is in the 30-50 range, and shock level is 15, I'm personally willing to let anyone in up to 10ppm (Maintenance is 3-6ppm). Just wear old suits you don't mind having fade. At that level, I'm uncomfortable swimming near 15ppm.

But if your CYA is in the 100-200ppm range, your normal maintenance range for chlorine will be 8-15 ppm and it is PERFECTLY safe to swim then--in fact you shouldn't swim in it if it's BELOW 8ppm--it might not be sanitary. Shocking will be at 25 ppm and while it should be OK to swim at 20ppm, my own superstition creeps in and I won't do it. Then again, if my CYA is 100, I'm draining and refilling with new water to dilute it down to between 30 and 60ppm.

[KurtV]

I thought the max in the Best Guess table was the upper limit for safe swimming (e.g. 6 ppm for a CYA level of 30-50 ppm). That certainly seems to be implied by the use of the word max.

[chem geek]

I'm not sure why Ben put in a column called "Max" or what it really means. The "Max" column corresponds roughly to a disinfecting chlorine level of 0.07 ppm which is equivalent to around 0.15 ppm FC with no CYA so is a very low amount of disinfecting chlorine. The "Min" column, for comparison, roughly corresponds to a disinfecting chlorine level of 0.03 ppm. The shock column doesn't correspond to a single disinfecting chlorine level, but is closest in the mid-CYA area to around 0.3 ppm disinfecting chlorine and that's equivalent to around 0.6 ppm FC with no CYA. So even shock level isn't as strong as most indoor pools with 1-2 ppm FC and no CYA.

The above discussion has to do with safety from the reaction rate of chlorine (i.e. concentration or strength) -- i.e. how fast it oxidizes your skin while in the water, for example. This is different from the actual FC level which determines the total amount of chlorine (i.e. capacity) which is more relevant if you were to swallow the chlorine since all of it will react and the rate is less important than the total amount of potential damage (in reality, most of the chlorine should get neutralized by saliva unless you drink an awful lot of it). For swimsuits, the disinfecting chlorine level is relevant while in the water, but when getting out and having it dry out, then the FC level is probably somewhat important though chlorine will also outgas as the water evaporates.

Richard

[CarlD]

Min and Max are the ideal target range Ben came up with for maintenance levels. Min is obvious but I'm thinking Max is the level beyond which you are just wasting chlorine unless you are shocking.

But in ALL chemical studies there's always a target range because a single number isn't necessarily meaningful.

[KurtV]

Richard,
Thanks. I'd seen that explanation from you before but had forgotten it.

I know you probably don't want to make a definitive statement like this, but I take from your explanation that, unless you're swallowing a pretty good amount of pool water, swimming at shock level (per the Best Guess Table) is at least as safe as swimming in an indoor pool.

[chem geek]

That is my opinion based on what I know about the chemistry. It's also consistent with my wife's swimsuit degradation experiences (indoor no CYA pool vs. outdoor CYA pool) and with corrosion issues in indoor pools and with the salt study (here (http://richardfalk.home.comcast.net/pool/Corrosion_and_Swimming_Pools.pdf)). It is not standard industry practice and manufacturers would likely disagree since, according to them, only FC matters in "real pools" (according to the Pinellas County study discussed in this thread (http://www.poolforum.com/pf2/showthread.php?t=6649)).

Richard