Nitrate problem

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I

irish18

0
Jul 29, 2011
11
Maple Glen Pa
I'm new to TFP and have had a pool for 3 years. It's a concrete pool approx 27,000 gallons. We've been having trouble keeping chlorine in our pool this year. A couple weeks back we were told our Cyanuric Acid was off the charts and we had to dump 40% of our water. I'm still having issues holding chlorine and todays test revealed a nitrate problem.... :grrrr:

I need help!!!!! The pool store says we need to dump the pool water and do an acid wash and start over! Do I really need to do this? I do have a lawn service that treats my lawn and I didn't have problems the last 2 years.

Here are my results from today:

Free Chl - 0.0
Total Chl - 0.5
Combined - 0.5
ph - 7.5
hardness - 253
alkanlinty -111
Cya - 86

I sure hope you guys can help... :-D

Bob
 
High CYA is a problem, but nitrates are not a problem. With high CYA levels you need to shock to very high FC levels, and keep FC high for a while, to kill algae. With CYA around 86, the FC level for shocking is in the low 30s. See the description of how to shock your pool in Pool School.

Unless you have a SWG, I suggest bringing the CYA level down further by replacing some more water. 86 is just manageable, but it is still very annoying to deal with when you have algae.
 
Jason beat me, but I still want to post ;)

I see no reason to acid wash, why were you told that?

Your CYA is still too high unless you have a salt water pool.

I am guessing you need to go through the shock process. Take a look at Pool School (the button in the top right), learn about the overnight chlorine loss test and the shock process.

At the very least you need to put some bleach in the pool right away. Plug your numbers into http://poolcalculator.com to determine what you need to add. I would at least go dump a gallon in there right now.
 
The pool store will tell you what they want in oder to sell products and such. They are in a business to make money (what business isn't?), but they will often try to sell you unnecessary products.

A high CYA is a problem unless you have a salt water generator hooked up to your pool. The only way to lower cya is to do a partial drain and refill. You can run a pool with that high of a cya, but it will cause problems if you ever need to shock, because the amount of chlorine it's going to take is, well let's just say a LOT.

With a cya of close to 90 you are going to have to maintain no less than 7ppm of chlorine every day, never letting it dip below that just to maintain.
 
You may not see algae yet, but with 0 Free Chlorine available, I'm guessing you will cloud up at the very least. I found this sight 2 years ago and after gettig my water balanced properly with a CYA level of between 40-50 I add nothing to my water except liquid chlorine or bleach. The ph and alkilinity remain in constant balance. I have NEVER had an algae outbreak and never had to use an algaecide.

A good test kit is a MUST to take control of your pool for yourself. I have been using the one that is recommended here and have used it for the past 2 years only having to buy some refills.
 
I'm not even sure what nitrates are. In the post above Jason said nitrates are not a problem and I would tend to think he would know. He knows a lot about pool chemistry and stuff. He is just one of the many people on here who helped my get my pool back in balance after struggling for 2 years with it.
 

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Great Value from Walmart is a good buy. Make sure to get only the regular bleach. Nothing scented of drip-free or anything like that. Any regular household bleach from any grocery store will do as long as the ingredients say 6 %.
 
Who told you you had a nitrate problem? Was it the pool store..Could it be that they said phosphates and you misunderstood it as nitrates? Not sure how they even would test for nitrates using the standard pool chemical tests. The pool stores routinely try to sell phosphate treating products (big mark-up profit maker for them). Maybe nitrate remover is the next big profit seller for them!

Nitrates could be coming from the lawn treatments if you are having your lawn chemically fertilized by company like Chemlawn. Make sure they don't over-spray or get any near the pool. Nitrates would be a food supply for algae but as long as you keep your FC levels up it won't matter what your nitrates/phosphate levels are.
 
Nitrates and phosphates are both required nutrients for algae. However, while phosphates can be lowered with phosphate removers, nitrates cannot be lowered except by water dilution. Nevertheless, neither level is important because chlorine alone can prevent algae growth regardless of nitrate and phosphate levels. Algae growth is ultimately limited by sunlight and temperature and can only double in population in 3-8 hours. If you have at least the minimum FC relative to CYA, then chlorine will kill algae faster than it can grow, regardless of nutrient level.

Of course, a pool high in algae nutrients is very "reactive" in the sense that the algae will grow relatively fast if you let the chlorine level get too low, but there are other ways to control such growth as "insurance" including the use of 50 ppm Borates and the use of Polyquat weekly. However, again, these are not necessary if one maintains the appropriate FC/CYA level (see the Chlorine / CYA Chart).
 
I've received my test results and here is what I have...
FC 5.4
Total Chlorine 7.1
CC 1.6
PH 7.3
TA 105
CH 234
CYA 93 (again they suggest 30-150 is normal)

I used the Pool calculator and it still tells me to replace 45% of my water because of CYA level. PH is a little low so was going to add 15oz of PH up. And also add 5lb of shock to due the CC level. Does this sound about right?

Any suggestions would be helpful.

Thanks!!!
 
Are you going to drain to lower CYA? If so, the amount of chlorine needed to shock will be different.

I'd shock after lowering CYA. Cheaper. Also, when you say add shock... what is that you're referring to? Shock is a name some chlorine products call themselves. Shocking the pool is a process, you will want to refer to pool school for information about how to do it. Bleach works just fine btw. Your shock product might contain CYA (depending on what it is). If you're keeping the CYA at 95, then you'll need to have enough bleach on hand to keep it at shock level till it passes the 3 criteria.
 

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