Green water. High CYA

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robstar

robstar

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LifeTime Supporter
Apr 13, 2015
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Mountain View, CA
Hi! I'm relatively new to TFP and have been trying to move my recently-acquired pool to BBB. I have very high CYA (~700, I think, having diluted my sample 4:1 with distilled water and getting a result of over 100) and although I've got 3 bags of Bio-active, I'd like to kill the algae first. I'm pH-okay, and my FC is now 25ppm (TF-100 kit), but is that enough to kill it? Being in California, there's a strong discouragement to draining. Suggestions?
 
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If your CYA is really 700( :shock: ) then you are just not going to be able to SLAM. SLAM level is about 40% your CYA level, putting your SLAM level at 270 FC... 25ppm isn't even slowing the algae down, you would need about 50 to even do that.

You can give the bio-active a shot, there has been extremely limited success as long as you follow their directions EXACTLY. Really though, I don't think you are going to make much of a dent and draining or reverse osmosis (if available) are about your only options.
 
robstar said:
Is 50 and 2x daily brushing likely to achieve anything?
Click to expand...

After a few weeks you should notice a change. Your arms should be much stronger, more tone, and you might need larger shirt sleeves. Your pool will look about the same though. Sorry, there really is no way around bringing down your CYA.
 
Hi, Rob,

Welcome to the forum. :wave: Figure out some way to drain 80-90% of that pool and start over. It is absolutely unmanageable and you will spend countless dollars trying to fight it.

I understand about the drought in California. You have an untenable situation and I don't see any other path.

BioActive doesn't work - get your money back if you can.
 
I brought FC up to the high 30s and covered the pool with a fairly opaque tarp to block the sun (since algae is powered by it) and have been filtering 24/7 for a few days now. Once in a while i measure a teeny bit (0.5-1.0) of CC, but mostly it's zero. I think it's starting to lose its green, but i'm not declaring victory yet. If it works, the next thing i'll try will be to lower the FC back down to 3 to give the Bio-Active a try.

Does algaecide actually work to prevent a recurrence, and if so, is there one that folks here recommend?
 
Adding a few grams of bromine to the pool might gelp in cases of high CYA. Bromine is not binded by CYA and will work as a sanitizer. The bed think with this is increased chlorine demand in the near future, but with the use of the solar blanket, the chlorine (and bromine) demand will decrease to some extent.
Copper is a very efficient algecide but you cannot use since it as it might stain the plaster. At Ph 7.4 and with a concentration of 0.5 ppm the risk is reduced, but without a Ph controller one cannot be sure that the Ph will remain at 7.4.
 
Robstar, I don't want to be discouraging, but I'm also afraid that just about any course of action you take that doesn't involve draining or Reverse Osmosis at such a high cya is going to ruin your chances at both actual ongoing sanitation of your water, let alone conquering algae. I'd hate to see you throw boatloads of money at the pool trying to slam at tht cya level only to then to end up having to drain it all.

The only person I've seen report success with bio active out of everyone whose tried it this year was someone who let their FC completely zero out.

Having the FC at zero (without the bio active) does sometimes cause a bacteria to grow that consumes cya, but the byproduct is ammonia and for each ppm of ammonia you need 10x the chlorine to break it down...if that ever hapened to your pool at 700 I can't quite imagine what it would take to conquer the ammonia.

Financially speaking, I suspect Reverse Osmosis treatment, while sounding expensive, would actually be the most cost efficient and environmentally conscious action to take, so look into that if possible.

If you CAN drain and refill, just remember that getting yourself to the right CYA level and engaging in TFP-style maintenance will reduce all the inefficient partial water changing, backwashing and other shenanigans that would go on over time if you don't get your cya under control. So a one-time changeout might actually be the better of the options even considering the current drought condition. I know that sounds strange, but possibly true.

Let us know what you decide to do once you've looked into your options. If you try the bio active, please track and report the efficacy because if you can make it work it will really help a lot of folks! We've been pretty disappointed to date with reported results, as we al held out a lot of hope for the product.
 

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If you manage to get the pool clean a Polyquat 60 algaecide might help in your case, but only after you get it cleared.

DO NOT add bromine to your pool. Once you do it becomes a bromine pool, which is not a great idea for outdoor pools.

From my HTC One via Tapatalk
 
Also, I'm not sure what the process will be, but unless they have or do something special, RO treatment cannot be performed on Alga laden water. If you inquire about this service, be sure to let them know and ask about that. Sorry to hear of your troubles, but I really think you should look into whatever it takes for a drain and refill. Even if your Cya number is off by half, it's truly unmanageable.
 
^sorry Rob, I steered you wrong on the R/O...if you find someone you can ASK, but I retract my opinion that R/O would be most cost effective in long run if you'd have to clear algae first because you would need astonishing amounts of FC to beat te algae. You're really back to the drain/refill scenario to get things under control, sorry to say.
 
Another alternative to the sodium bromide treatment to work around the high CYA is to use an ammonia product that produces monochloramine. You'd need the FC much lower at around 3 ppm FC to use such a product, but it has the advantage that you can get rid of the monochloramine once you are done. This would only be an interim solution and does not fix the fundamental problem of the high CYA.

Why are you wanting to get rid of the algae before using the Bio-Active? The only few times that product seemed to do anything (and most of the time it seemed to do nothing) is when the FC was very low (see this thread for a recent example). A higher active chlorine level seems to prevent the product from working (when it works at all). As Dave noted, you should see if you can get your money back for that product. If not, then you could try it but need to get the FC much lower first. Of course now that you've got your FC up high it may take a while for it to drop unless it gets used up more quickly from the algae.

I noticed the pool has a cartridge filter. Does it also have a pool cover that would prevent winter rain dilution? The previous owner probably used Trichlor tabs and built up CYA over the years, though it does not take long. For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases CYA by 6 ppm.
 
i think my main concerns with algae were about staining, and about water cloudiness making CYA testing difficult, but it's really not *that* cloudy, so i guess i should go straight for the much-anticipated Bio-Active study. i assume leaving the pool exposed to the sun to burn off the chlorine will also bring back the algae as the FC falls.

Did this graph https://www.troublefreepool.com/~richardfalk/pool/HalfLife.gif seem to "hold water", as it were? That is, if i have a TON of CYA and a FC of 40 now, 9 hrs of sun (let's call that one day) should drop it to 20, then another day to 10, 3rd to 5, 4th to 2.5, and then i can play with Bio-Active, as it requires sub-5 (ideally 2-3 FC)? i'll test, of course, but does that generally sound like i'm calculating the dissipation correctly?
 
I was just reading up on drought restrictions for your area. Does your pool pad happen to have a hose bib plumbed in? If so, you could use your pool water to water trees and lawn on the allowed days and the fresh water to refill the pool. You could use ChemGeek's suggestion for killing the algae and work on slowly replacing the water over the summer.
 
robstar said:
Did this graph https://www.troublefreepool.com/~richardfalk/pool/HalfLife.gif seem to "hold water", as it were? That is, if i have a TON of CYA and a FC of 40 now, 9 hrs of sun (let's call that one day) should drop it to 20, then another day to 10, 3rd to 5, 4th to 2.5, and then i can play with Bio-Active, as it requires sub-5 (ideally 2-3 FC)? i'll test, of course, but does that generally sound like i'm calculating the dissipation correctly?
Click to expand...

That graph was done assuming that the rate of breakdown of chlorine bound to CYA was at a fixed proportionate rate and that the chlorine unbound to CYA was breaking down at a higher fixed proportional rate. What is missing from that graph is the CYA shielding effect that we discovered later. So higher CYA levels will slow down the breakdown more than what I had assumed. So with your very high CYA level (if it's really around 700 ppm) you may find that the rate of FC drop is rather slow. It would be useful for us to know that actual rate, assuming your pool gets full sun. So why not measure over one or two days to see what it is.

However, after letting it drop for a day or two (for science sake), then if you wanted to drop the FC faster you would add a dechlorinator to the water. Hydrogen peroxide is the easiest to use and has the least side effects. For your 15,000 gallon pool, it would take 2.4 gallons of 3% hydrogen peroxide to drop the FC by 10 ppm so that's not very practical. Baquacil Oxidizer is 27% hydrogen peroxide so you'd only need 1/9th as much so 4-1/3 cups for a 10 ppm FC drop. Pool stores also sell chlorine reducers (usually sodium thiosulfate), but that is probably more expensive.

I don't hold high hopes for the Bio-Active since it's only worked a small percentage of times and in your case your pool already has algae so if you do this your algae may get worse at first though the Bio-Active company claims that during the treatment it inhibits algae (but we saw water get cloudy during one person's treatment while for another person it didn't -- again, very mixed results).
 

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