Possible Nitrate Troubles

[mminetti]

I have a 24,000g, vinyl, IG, sand filter, pool in Central NJ. I use just a floating puck for chlorine. I opened the pool in early April and have been struggling with the chlorine ever since. All other levels have remained at what you'll see below with no chemicals. In the beginning I was dumping 3-4 bags of shock, taking an instant strip reading and showing zero chlorine (pool store confirmed). I have used both the filter perfect and line cleaner perfect from Natural Chemistry (can't remember the name) products. I have also used PhosFree and Aqua Finesse. As of last week if I put 2 bags of shock in the pool I was able to get a dark purple reading on the sticks, however by the next morning the reading was back to either nothing or a very light shade of purple. I most recently shocked the pool on Wednesday night. Today I took a water sample to the pool store albite after it rained both Friday all day and today all day:

Today's Readings:
fc: .16
tc: .35
cc: .19
pH: 7.3
Hardness: 198
Alk: 90
Cyanuric: 79

I also asked them to perform a Nitrate test which was only a stick test but came back in the 1-2 range (between the first and 2nd pink reading on the stick). Nitrites came back zero. I know if nitrates is the problem draining is my only solution, but I can't find what is an "acceptable" range for nitrates.

Does this sound like a Nitrate problem or something else? Any help would be appreciated.

Thanks,
Mike

 

[jblizzle]

Well, now that you have tried all the "magic bullets" ... how about reading Pool School and learning to truly understand the chemistry in the pool?

Phosphates = meaningless
Nitrates = meaningless.

You problem is the continues use of trichlor pucks which add chlorine and stabilizer. The chlorine is consumed, the stabilizer builds up. To keep a clear pool, the required FC is a function of the CYA level ... as the CYA goes up, you have to maintain higher FC ... puck will not be able to do this.

Your CYA is too high, water replacement will lower it, then you need to switch to liquid chlorine so you stop adding any more stabilizer.

Oh, and to follow the advice we provide (for free), you will really need to get yourself one of the recommended test kits and stop trusting the pool store ... who are in business to make money ... and by your post, they have gotten plenty of your money at this point.

 

[fast1971chevelle]

Excellent advice jblizzle...I would listen to him and save yourself a ton of money.....Mike

 

[bk406]

A couple of things.
Your CYA is high, as mentioned above, but not terrible. But the test from the pool store may be inacurate. The phospates are meaningless, so yea, ignore that. The nitrates, or potential nitrates in the water are not necesserily meaningless. Their presence will increase the chlorine consumption until they are burned out in the form of combined chlorine. Hard to tell from your test results, but it apppears the CC may be high?

At any rate, something is using chlorine in your pool. You need a proper test kit and keep you pool at shock level based on your CYA number until your chlorine is stable, and the CC numbers are <0.5 ppm or better yet, zero.
Read pool school to learn how to shock your pool, and get a proper drops based test kit.

Is your water clear otherwise?

 

[mminetti]

The strangest part is that the pool is crystal clear; of course water temps in NJ have been extremely cold for April/May so Algea would have a tough time growing anyway.

I appreciate everyone's feedback. It's probably not an exact science but to drain the pool to reduce the CYA levels how much do you think I need to remove? I guess in doing so I'd help both the CYA issue and potential Nitrate issue.

Thanks again,

 

[JasonLion]

Nitrates are not a problem. The nitrate level has no direct effect.

This sounds a little bit like an ammonia issue, though if it was ammonia the CC level would be higher.

Regardless the solution is to shock the pool as described in Pool School (not as described by the pool store).

 

[bk406]

I wouldnt do any water drain at this point. Get a test kit, perform each test, and post up the numbers. In the mean time, you can add chlorine to your pool, just do it with bleach.
For a CYA value of 80, your shock number is 31 ppm. To raise the FC to 31 from zero, you need to add 16 gallons of 6% bleach. And thats assuming your CYA is truely 80.

 

[Richard320]

The strangest part is that the pool is crystal clear; of course water temps in NJ have been extremely cold for April/May so Algea would have a tough time growing anyway.

I appreciate everyone's feedback. It's probably not an exact science but to drain the pool to reduce the CYA levels how much do you think I need to remove? I guess in doing so I'd help both the CYA issue and potential Nitrate issue.

Thanks again,

It is an exact science, actually.

IF - and that's a big IF - CYA is 79 and you want it to, say, 50...(79-50)/79 = 37% replacement. Tap water has no CYA. Check the math. (.63 * 79) + (.37 *0) = 49.77. IF CYA is 79. It's a tough test to master and pool stores are notoriously bad about it.

I have no idea what my nitrate level is. Nor my phosphate level. Nor my Total Dissolved Solids. Never been tested. They don't matter. But my water is so clear I can toss a coin into the deep end and call heads or tails from the deck.