Baffled by RO vs tap PO4, TDS readings

[Dego Red]

For as long as I've been in this hobby, I've never been able to keep SPS from browning, not one. After covering every base, phosphate had to be the culprit. Determined to find the source this time, I started testing everything. A few things just don't add up.

 

I've always used Glacier RO water from Albertsons since its 1mi away and I only have a 35g system. TDS has measures 2-3, so I foolishly assumed that the PO4 readings must be lower than tap...right? Well here's what I got tonight:

 

RO TDS: 2

RO TDS immediately after transferring to my ATO reservoir: 11 (say what?!)

RO PO4 reading: Somewhere between 0.1-0.2, needs to be checked by a photometer

Tap TDS: 57

Tap PO4: Between 0-0.1, but roughly half of the RO compared side-by-side

 

My reservoir was cleaned the same way as my transfer buckets before the test - vinegar and tap - and never gets anything but RO.

 

Can anyone explain these numbers or seen something similar?? I'm about ready to start conditioning my tap water until I can get my hands on an RODI unit in the hopes I get better results.

[lewisriverfisherman]

from what i can tell from your numbers and what you have said is that you are only using RO water this might be part of your problem. you aren't using the DI part of the equation that filters out the metal's part of the water and that is what the DI does. I am also wondering what you are using for lights. sometimes brown corals means that you aren't using high enough lighting.

[Dego Red]

from what i can tell from your numbers and what you have said is that you are only using RO water this might be part of your problem. you aren't using the DI part of the equation that filters out the metal's part of the water and that is what the DI does. I am also wondering what you are using for lights. sometimes brown corals means that you aren't using high enough lighting.

 

400W MH (20K) over a 29g display - lights shouldn't be an issue, especially not the way clams grow for me.

 

My question is, how can unfiltered tap water have 1/2 the phosphate RO water does? My only thought is the source water for the RO is poorer quality than the city water (but, again, why?) and relies on the process for taste since it's technically just drinking water.

[jackaninny]

Could be a poor maintenance job on that machine like leaving filters on there too long or not servicing the machine often enough.

 

You could also try swapping out your ATO container and see if that's the source.

[impur]

400W MH (20K) over a 29g display - lights shouldn't be an issue, especially not the way clams grow for me.

 

My question is, how can unfiltered tap water have 1/2 the phosphate RO water does? My only thought is the source water for the RO is poorer quality than the city water (but, again, why?) and relies on the process for taste since it's technically just drinking water.

 

Because we have really good water here in Oregon, and because the place you are getting your water doesn't change their filters very often. Filters cost money. TDS is Total Dissolved Solids. That is different than PO4/NO3 etc. Another possible cause is PO4 leeching from your rocks, which is most likely the culprit. Did you test the PO4 of your tank? If its higher than both water sources, your problem is in the tank.

[Dego Red]

Could be a poor maintenance job on that machine like leaving filters on there too long or not servicing the machine often enough.

While they do have "last service date" on the machine, I wouldn't necessarily trust that either. But since the TDS is in the same range as anyone else's RO (pre-DI), I've never had reason to suspect it.

 

You could also try swapping out your ATO container and see if that's the source.

Water was tested prior to to transfer to the ATO res, straight from the machine.

 

Because we have really good water here in Oregon' date=' and because the place you are getting your water doesn't change their filters very often. [/quote'] TDS ranges are always the same (2-4). The only thing I can think of is if the filter lasts long enough to keep the TDS low, but is also long enough to trap phosphates to the point where they'll leach out in higher numbers.

 

TDS is Total Dissolved Solids. That is different than PO4/NO3 etc.

Well of course. Point is, unless the source water is different, what's causing the high phos?

 

Another possible cause...

Tank phosphate is right around 0.05ppm, but needs to be verified by a photometer. Either way, its about half that of the RO water due to my reactor (Rowaphos). Focus here is just the freshwater.

 

Regardless of the source, guess I'll have to go a bit 'overboard' (for tank size, anyway) and get an RODI. I was simply curious as to if anyone else experienced the same. Guess I'll tell the wife we just need a bigger tank to make efficient use of it.

[impur]

Well you've discounted just about every single possible cause we can come up with. It isn't something magical, it has to be one of the things above.

 

How old are your test kits? Have you had the results double checked?

[ReeFit]

For as long as I've been in this hobby, I've never been able to keep SPS from browning, not one. After covering every base, phosphate had to be the culprit. Determined to find the source this time, I started testing everything. A few things just don't add up.

 

I've always used Glacier RO water from Albertsons since its 1mi away and I only have a 35g system. TDS has measures 2-3, so I foolishly assumed that the PO4 readings must be lower than tap...right? Well here's what I got tonight:

 

RO TDS: 2

RO TDS immediately after transferring to my ATO reservoir: 11 (say what?!)

RO PO4 reading: Somewhere between 0.1-0.2, needs to be checked by a photometer

Tap TDS: 57

Tap PO4: Between 0-0.1, but roughly half of the RO compared side-by-side

 

My reservoir was cleaned the same way as my transfer buckets before the test - vinegar and tap - and never gets anything but RO.

 

Can anyone explain these numbers or seen something similar?? I'm about ready to start conditioning my tap water until I can get my hands on an RODI unit in the hopes I get better results.

 

 

The simple answer is the source. readings vary at every location, in portland TDS readings can go from 6 to 40TDS, depends on your source, your plumbing age and type, etc. Our water up here in vancouver is 160's TDS and is acceptable to have 10ppm nitrates as a tolerance. Now the kicker is, unfortunately, the standard R.O. membrane does not remove nuisance chemicals like phosphate, nitrate, or silicates. Either a High-S membrane has to be used and or the addition of DI resin filters are a requirement to remove PO4 traces out of a water supply.

[SquidHC]

Have you considered running a phosBan reactor with appropriate media, in your ATO bin?

[Jay]

I have a duel DI chamber with Duel tds meters for sale....if ya need one. Only 35 bucks...

[JimmyK]

As stated above..TDS does does not meausre phosphates and other metals. Possible that your jug or ato is leaching phosphates? Without the DI resin the RO only does not remove phophate. Get a RO/DI unit you will wonder why you did not get it as soon as you purchased the tank.....

[Jay]

If you are running carbon in your tank it needs to go into a phosphate reactor before back into your tank. Lots of brands of carbon leech p04 into the water. You basicly need 2 phosphate reactors. One for carbon then install it inline with a reactor with GFO. Also...cal reactor effluent should go through gfo also..Reactor media that says phosphate free....not necessarily the case all the time. Ive had issues maintaining bright colors also. I almost went to the extreem of buying all that ZEO stuff and the probiotic stuff....then realized that bills are more important to me then bright sps corals. I always look back at how happy I was with my old 55 gallon tank and the soft and stonys that were in it. Someday I will have another sofyt/stony/anemone tank..

 

Jay

 

[Jay]

As stated above..TDS does does not meausre phosphates and other metals. Possible that your jug or ato is leaching phosphates? Without the DI resin the RO only does not remove phophate. Get a RO/DI unit you will wonder why you did not get it as soon as you purchased the tank.....

 

Agree....buy a ro unit

[blown65]

The phosphate from the store is probably from the post Carbon filter. All residential R/O systems use a post filter using carbon and most leach phosphates back in.

 

Either buy your own R/O DI setup, or get a small pump and DI filter so you can polish it off at home.

[Dego Red]

...Lots of brands of carbon leech p04 into the water...

The phosphate from the store is probably from the post Carbon filter. All residential R/O systems use a post filter using carbon and most leach phosphates back in...

There! *These* are the types of answers I'm looking for. Not the 'where', but the 'why'. We're beating a dead horse here with the TDS vs PO4 argument - I already stated that I knew long ago that they are not the same thing. The statement was only made as an assumption that there should be some correlation between the two, that possibly being the health or age of the filter.

 

Regardless, I already know where PO4 is coming from, and the carbon filters are the most logical answer if they're known for leaching. I'd often seen running both in a single reactor, but now I see why! Learning something new every day.

 

I've heard good things about the Water General RODI units, and for $150 shipped it seems like a nice setup. Anyone here have experience with them?

[blown65]

Its very easy to test it BTW. Since we sell residential systems of all types, I've tested a couple different Carbon filters and they both leach PO4. I keep meaning to test the bulk Carbon we get.

[Algae]

There! *These* are the types of answers I'm looking for. Not the 'where', but the 'why'. We're beating a dead horse here with the TDS vs PO4 argument - I already stated that I knew long ago that they are not the same thing. The statement was only made as an assumption that there should be some correlation between the two, that possibly being the health or age of the filter.

 

Regardless, I already know where PO4 is coming from, and the carbon filters are the most logical answer if they're known for leaching. I'd often seen running both in a single reactor, but now I see why! Learning something new every day.

 

I've heard good things about the Water General RODI units, and for $150 shipped it seems like a nice setup. Anyone here have experience with them?

 

There are a few of us that have Water Generals. Very good, well built units.

[ReeFit]

I find it hard to believe that the carbon is leaching that much po4 back into the water. most high grade carbons unless its the worst possible grade of carbon on the market that you wouldn't even want it to touch your tank water let alone drinking water, usually only leeches about .02-.03 of p04 back into the water and once it goes stale it will not leach any more into the water. Its easy to test carbon by putting a tablespoon of carbon in a gallon of water and test your phosphates in an hour. and besides most reef tanks do well with .02-.05 phosphates in the water. you do need phosphates in your water to sustain life and taking it all out can cause problems. I do not run gfo after my carbon canister and i run carbon 24/7.

[Dego Red]

I find it hard to believe that the carbon is leaching that much po4 back into the water. most high grade carbons unless its the worst possible grade of carbon on the market that you wouldn't even want it to touch your tank water let alone drinking water' date=' usually only leeches about .02-.03 of p04 back into the water and once it goes stale it will not leach any more into the water. Its easy to test carbon by putting a tablespoon of carbon in a gallon of water and test your phosphates in an hour. and besides most reef tanks do well with .02-.05 phosphates in the water. you do need phosphates in your water to sustain life and taking it all out can cause problems. I do not run gfo after my carbon canister and i run carbon 24/7.[/quote']

So I guess the question is, what's the saturation level PO4 in carbon before leeching (if that indeed is the source), especially those in water purification machines? And at what usage/age does it become a problem? Answers we'll probably never get, but interesting nonetheless.

 

Just by eyeball my PO4 level in the tank is 0.03-0.05, so I'm still in range running fluidized GFO. I just want to keep my one and only SPS alive for as long as possible - and dare I say - actually see some growth! I'm gonna bring a sample of all three to the LFS this weekend just for the sake of interest and hopefully order the RODI today or tomorrow.