Advice Needed - High CYA, High Nitrates, and Lots of Algae

[aylad]

I typed a very long response to this thread about 1/2 hour ago, but when I tried to post, I got a message saying that the forum wasn't accepting new posts. So...I emailed it to Ben, but it's not here yet. Later this evening, when I can get back to the computer I was on at the time, I'll try again.

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OK, here it is...

What testing method did you use to come up with your test results? We very highly recommend drop-based testing here, because it is much more accurate than strips or computers are. Do yourself a favor and take a look at the K-2006 test kit in the link in my sig--it's going to be required if you're going to manage this pool with your CYA level that high.

You can fix the pool water in two ways...first, you can drain/refill part of your water to lower that CYA, or you can simply run a high CYA/high chlorine pool (which would be my pick of the two). Take a look at the "best guess chlorine chart" in my sig for a better explanation, but basically because your CYA is so high (due to the dichlor/trichlor use), you have to maintain higher chlorine levels to compensate. In your case, with a CYA of 160-ish (are you sure that's right?) you need to shock the pool up to a chlorine level of 25 ppm and hold it there, brushing daily and cleaning the cartridge as your pressure indicates, until the pool clears. It will become blue/cloudy at first, and then you can finish filtering out the dead algae After all the algae is gone, then you just have to maintain your chlorine levels between 8-15 ppm and you shouldn't have any further problems. (At this point, I'd switch to bleach, liquid chlorine, or a SWCG, though--if you keep using the dichlor or trichlor, that CYA is just going to skyrocket to the point where draining/refilling isn't an option).

I run a higher CYA pool than most folks around here--80-90 ppm, sometimes higher--and I like it that way. I don't have to dose everyday, and there are zero complaints from the swimmers I have about the water quality,.

[capshockeyfan]

Thanks much to the folks who have responded to this thread!

A local pool store is where I have obtained the results I posted in my initial message; I believe they use a computerized tester. My wife stopped by the store today to get the water tested and gave me the results over the phone; I'm home now and everything I posted above matches the printout.

On my way home from work, I picked up six 96oz jugs of 6% bleach. I brushed the pool when I got home, changed out the cartridges, lowered the water level a couple of inches and refilled with tap water from our well. I then poured all of the bleach into the pool; I will get more bleach in the pool starting tomorrow. (Hopefully it is okay to not add all of the bleach at once.)

I will get the pool water re-tested tomorrow morning on my way to work and will post a follow-up message here ASAP. I will also get a sample of the well-water tested. My wife will stop by our local Walmart and get the recommended testing kit... I'm not chemically savvy, so hopefully it's simple to use!

I have added my pool info into the pool chart as per Waterbear's request. (I was way off on the HP of our pump in my initial post! )

Thanks again for the quick replies; you have given me some hope that my "swamp" might actually become useable again!

[aylad]

If my math is correct, 6 96 oz containers of bleach = 4.5 gallons, which will raise the FC in a 36K gallon pool by 7.5 ppm, which is not nearly enough to clear up an algae bloom. Each gallon of 6% bleach in a pool that size will raise your FC by 1.7 ppm, and with your high CYA you need to get it up to (and keep it at) 25 ppm.However, you need to take a look at your well water analysis before you do this, because if you have metals in the water, then raise the chlorine that high, you may end up with a tea colored pool. So post your metals analysis here before you shock the pool!

The hth kit is not hard to use, but you'll have to force the chlorine test to read higher than it's supposed to by diluting your sample and multiplying (see this thread http://www.poolsolutions.com/gd/how-...d-testkit.html). That's why you need the K-2006--it will accurately test chlorine levels to at least 50 ppm without guessing.

[waterbear]

As I said in my post you will need 19 96 oz jugs of 6% bleach!

[waterbear]

(Hopefully it is okay to not add all of the bleach at once.)

Nope, Won't do the job. It ALL has to be added at once, the water retested, and more added as it is consumed to maintain the chlorine level at 25 ppm or greater.
A Taylor K-2006 will make things much easier for your. The kits from Walmart are just an inexpensive stopgap measure unti you get a good kit which will have to be ordered on the internet most likely.

[capshockeyfan]

I stopped by our local pool shop this morning on my way to work and they tested samples of our pool water and well water for nitrates. They are using a computerized system and it only gives out readings on nitrates up to 80, which is where our pool water is at... so at this time, I do not know how high our nitrates actually are, just that they are at least 80.

The good news is that our well water was clear of nitrates, so the new water I can add is not making the problem worse.

Aylad - Unfortunately, I did not see your post until I got to work, so I did not have the well water tested for metals yet; I will do so tomorrow. Just to confirm, the metals you are referring to are the iron and copper that the pool shop included in the test yesterday? (Are there any other metals I need to have tested for?)

The pool shop folks said it was useless to add chemicals to the pool until the nitrates were lower and the only thing I can do is replace the water. They were really busy and did not have time to run a full water test; their thought was that if the nitrates are through the roof, it does not really matter what the other results were.

My wife is picking up one of the Walmart pool water testing kits today and I will post those results here tomorrow; I will also order one of the Taylor K-2006 kits you are recommending. Given that it will take a few days for that kit to arrive; I'm hoping I can make some progress on the pool situation while waiting for the better kit.

I have thought about possibly running a high CYA/chlorine pool; before I make that call, can you tell me if people with sensitive skin might have a reaction to this type of water?

Waterbear - Sorry I screwed up with only adding a partial amount of the bleach; my plan was to add the full amount over the weekend when I have more time to devote to the pool. I thought it would be okay to pick up a portion of the bleach on my way home from work last night to get things started and then add the rest over the weekend. Lesson learned!

Given that my pool has very high CYA and nitrates, it is looking like at least a partial drain and replace will have to be done. If so, do you folks feel it is best to just drain the whole pool and start over with trucked in water; or would a gradual drain and replacement (6,000 gallons at a time) be a better way to go?

If we go with a gradual refill, my thought was to try and kill two birds with one stone if possible... get the chlorine levels up high right now to kill the algae bloom; I can then vacuum out the dead algae when I lower the pool water in preparation for the arrival of the trucked-in water. If I go this route, at least my pool will be free of algae once we have the nitrates and CYA in check.

[aylad]

I would stop worrying about the nitrates. If you kill the algae in the pool, then the nitrates don't matter. If you want to drain/refill part of the water, then I would drain/refill before killing the algae so that you're not wasting all the chlorine to kill the algae, then draining that nice, clean water out of the pool. However, I still think you could just stop using stabilized chlorine and run a higher Cl pool,, especially if you want to get swimming during this season. Folks with sensitive skin shouldn't have any problem with this type of water--a pool with a CYA of 160 and Cl of 10 is no more irritating to the skin than a CYa of 30 and Cl of 5. The chloramines are normally what will irritate the skin, but if you keep your chlorine at the appropriate level, you shouldn't have those anyway.

It's your pool and you are the one to ultimately make the decision. However, I want to caution you that completely draining the pool, if you have a high water table, can cause the pool to literally float out of the ground. If you decide to go that route, I'd make sure you have some professionals to help do the job.

[AGPoolNewbie]

I was reading your thread and although I am not knowledgeable enough to offer any insight directly to help with your problem, it did raise a question in my mind, and I hope I am not wrong in asking it here. Capshockeyfan has a problem with CYA levels being very high. I understand that you can maintain high levels of CYA as long as the chlorine levels are in somewhat of a proportionally high level. My question is this; Does CYA ever break down or go away through its normal chemical process or reaction with chlorine? Is it ever consumed? If so, how long does it take for CYA to break down and what chemicals does it break down into?

[aylad]

It takes a long, long time for CYA to break down under normal chlorination levels--I believe it's something like 2-3 ppm per month. CYA can and does break down under algae/swampy conditions--it breaks down into 2 or 3 different things, but one of the most prominent here is ammonia--which creates a HUGE chlorine demand to overcome.

If this OP will stop using stabilized chlorine products, the CYA will eventually come down on its own through splashout and filter backwashes--but it will take awhile.

Janet