Nitrate > 160ppm, Phosphates > 125ppb, is SWCG in danger?

[scottts]

A recent SWCG install thread on the site prompted me to read my IC-40 manual more closely. In it, it very clearly indicates Pentair really doesn't want nitrates in the pool. They say no more than 10ppm and greatly urge 0ppm. They also don't like phosphates above 125ppb.

Using an API freshwater aquarium test, my nitrates are off-scale >160ppm. Using the Taylor phosphate drop kit, my phosphates are between 125 and 250 ppb.

The 2019 water report for Gilbert AZ indicates an average 3.6ppm nitrates in the fill water. They don't show results for phosphate. So I'm clearly going to gain nitrates due to evaporation.

I'm not worried about algae, I keep my FC well above the min. I'm worried about why Pentair is so worried about nitrates? Should I be worried? I presume draining is the only way to reduce nitrates. Is there a natural breakdown process for nitrates?

 

[JamesW]

I'm worried about why Pentair is so worried about nitrates?

Email them and ask them.

 

[scottts]

Email them and ask them.

Way too obvious, but good, idea.

EDIT - email request for information sent.

 

[mknauss]

Be sure to post what they say. Especially the science behind their statement.

 

[JamesW]

I wouldn't worry about nitrates.

Do an OCLT to confirm that there's no chlorine loss overnight.

Overnight Chlorine Loss Test

 

[scottts]

That’s exactly what I asked them for, the science. We’ll see.

I don’t have any water issues. My post is really about cell life not algae.

 

[mknauss]

Cell life is based on how much chlorine you generate and how often you clean the cell with acid.
Manage your pool water chemistry so you never have to acid clean the SWCG.

In 6 years I have never had to clean my SWCG. And I have no idea what my nitrates or phosphates are. They are immaterial.

 

[scottts]

Oh, I do manage my chemistry. Haven't had to clean the cell in the life of the pool (10 months). I target -.1 lsi (lsi because that's what the intellichem reports)

I guess I'm just trying to find out if Pentair views nitrates and phosphates as bad because they could make a under chlorinated pool grow algae that the SWCG can't catch up with, or if there are chemical reactions in the cell with nitrates and phosphates (I know there are some theoretical possibilities here) that damage or shorten the life of the cell.

 

[scottts]

OK, I got a reply from Pentair.

I asked:

I have an IC-40. The manual warns against more than 10ppm nitrates in the pool water and more than 125ppb phosphates. Why? What's the science behind these warnings? Thanks!

Pentair replied:

They will eat up the chlorine that the unit is making. It is advised to follow those guidelines as close as possible so that you don't end up with chemistry issues in the pool.

I followed up:

Ok. So the notates (my spelling error) and phosphates don’t directly damage the ic-40 chemically? They just feed algae that eats chlorine causing the cell to work harder?

Pentair answered:

Correct - they simply eat up the chlorine that the cell is making - I think when you get that under control - that will take care of your issues. Let me know in the next week or two if that resolved your issues with Algae vs having enough chlorine in the pool.


So there it is from the horse mouth. I think what he means is they feed algae that will eat the chlorine.

Just to reiterate I keep my FC high (8-10ppm at 30 cya) I don't have a water problem currently. I just wanted to know why Pentair has seemingly strong warnings in their manual for the intellichlor.

 

[mknauss]

The second response was the more correct one. First one claimed that nitrates and phosphates consume chlorine. They do not. They enhance algae that chlorine is then expended on. TFPC is based on eradicating algae. So who cares what level of nitrates or phosphates there are.

 

[scottts]

Maybe one might want to know your nutrition status in your pool so maybe you run higher FC for more margin in case of a slip-up. People with 0 nutrients could maybe run a bit lower (still within the recommendation of course) saving a bit of cell life. Knowing how much nitrate is in my pool I will certainly run at the high end.

I think that knowing nutrient levels can help optimize the lifetime of an SWCG. How much running at the bottom of the FC range versus the top+ could save? I don't know.

 

[Saturn94]

Maybe one might want to know your nutrition status in your pool so maybe you run higher FC for more margin in case of a slip-up. People with 0 nutrients could maybe run a bit lower (still within the recommendation of course) saving a bit of cell life. Knowing how much nitrate is in my pool I will certainly run at the high end.

I think that knowing nutrient levels can help optimize the lifetime of an SWCG. How much running at the bottom of the FC range versus the top+ could save? I don't know.

I doubt it makes any noticeable difference in cell life. Assuming no algae and you only use the SWCG to maintain the FC level, your daily FC consumption will be pretty much the same no matter where you maintain FC in the recommended range.

 

[Saturn94]

OK, I got a reply from Pentair.

I asked:

I have an IC-40. The manual warns against more than 10ppm nitrates in the pool water and more than 125ppb phosphates. Why? What's the science behind these warnings? Thanks!

Pentair replied:

They will eat up the chlorine that the unit is making. It is advised to follow those guidelines as close as possible so that you don't end up with chemistry issues in the pool.

I followed up:

Ok. So the notates (my spelling error) and phosphates don’t directly damage the ic-40 chemically? They just feed algae that eats chlorine causing the cell to work harder?

Pentair answered:

Correct - they simply eat up the chlorine that the cell is making - I think when you get that under control - that will take care of your issues. Let me know in the next week or two if that resolved your issues with Algae vs having enough chlorine in the pool.


So there it is from the horse mouth. I think what he means is they feed algae that will eat the chlorine.

Just to reiterate I keep my FC high (8-10ppm at 30 cya) I don't have a water problem currently. I just wanted to know why Pentair has seemingly strong warnings in their manual for the intellichlor.

This reminds me of something I read recently about removing phosphates. The person said removing phosphates from the pool was like tearing out your garden to keep bugs from eating it. Kill the bugs instead and you can keep your garden.

I thought, wow, this guy knows his pool care! But then he went on to say you need to shock regularly and use algaecides to prevent algae in the first place.

 

[mguzzy]

Kill the bugs instead and you can keep your garden

Good bugs, bad bugs.. makes no matter that you also killed the bees that pollinate the flowers.. I don't think I'm liking that analogy.

The last time I tested for nitrates in water I was on a research project 30 yeares ago, Does Leslies even have a dip stick for nitrates?... If you want to really get all the nutrient chemicals out of the water you better replace you SWG with a still so you can fill your pool with distilled water.

 

[Newdude]

All my equipment is Pentair and I love it. But as above they clearly should stick to their lane which is manufacturing. The big brands favor the pool stores and give better warranties as a way to have more people use them. It’s no surprise they follow a similar form of pool MISmanagement.

 

[scottts]

From the practical standpoint of taking care of a pool, I understand the "just keep chlorine in range and forget about nitrates and phosphates" recommendation. No argument there.

But there are secondary questions in some cases. For example, how does 160+ppm of nitrates affect the electrolysis of various things in the cell. I for one am interested in understanding if there are typically non-measured things, like nitrates, that can enhance hydrogen production in the cell and therefore impact ORP negatively. Maybe that question belongs in the Deep End.

Looks like Taylor might have one nitrate test kit K-8035, but it's expensive. Much cheaper to use the API aquarium nitrate test drops if you want to test.

 

[Saturn94]

Good bugs, bad bugs.. makes no matter that you also killed the bees that pollinate the flowers.. I don't think I'm liking that analogy.

The last time I tested for nitrates in water I was on a research project 30 yeares ago, Does Leslies even have a dip stick for nitrates?... If you want to really get all the nutrient chemicals out of the water you better replace you SWG with a still so you can fill your pool with distilled water.

When it comes to actual gardening, I agree with you. But I have no sympathy for “bugs”, ie algae, in my pool.