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GEEK
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Discussion Starter · #1 ·
Anyone here purchase RO water from their LFS and tested it? I recently bought a few gallons and tested it before using it. This is the first time purchasing water and these are the parameters I got. I use the API test kits.

pH: 7.6
GH: 5
KH: 3

I am trying to explain these results. Are these results within a range to be expected with RO water? I would have expected a neutral pH, and KH and GH close to 0. Am I off in my expectations, are my test kits off, or is the LFS not really selling RO water?
 

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548 Posts
wow, rip off...
It's better to get RO water from refill stations.(used for drinking)
I sometimes use it for top-offs. Only 25 cents/gallon
 

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RO filters are based on percent removal which typically ranges from 75-90%. So if they are starting with water that has GH of 18, then the meaurement you got would be 5. So if you're running well water through it, which typically has a lot of minerals, then RO will leave a lot in. If the water source is surface water from snowmelt or rain, the water will have much less minerals and the RO unit will produce cleaner water.

Because RO has the potential to leave a lot of stuff in the water, DI cartridges are used which will bring that 75-90% removal up to 99.99%. So if you can find RO/DI water, it will be cleaner than just RO water.

Also, the pH of pure water will typically be around 6.0 because atmospheric Carbon dioxide dissolves into the water and turns it slightly acidic.
 

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GEEK
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664 Posts
Discussion Starter · #5 ·
RO filters are based on percent removal which typically ranges from 75-90%. So if they are starting with water that has GH of 18, then the meaurement you got would be 5. So if you're running well water through it, which typically has a lot of minerals, then RO will leave a lot in. If the water source is surface water from snowmelt or rain, the water will have much less minerals and the RO unit will produce cleaner water.

Because RO has the potential to leave a lot of stuff in the water, DI cartridges are used which will bring that 75-90% removal up to 99.99%. So if you can find RO/DI water, it will be cleaner than just RO water.

Also, the pH of pure water will typically be around 6.0 because atmospheric Carbon dioxide dissolves into the water and turns it slightly acidic.

Thank you for the explanation. I checked the values out of my tap this morning and the values I got were:

pH: 7.6
GH: 7
KH: 4

The water supply to my home is the same as the LFS. Assuming a 75% reduction of mineral content with a functioning RO unit, I would still have expected lower values in the RO water that I purchased.

I would like to give the benefit of the doubt that the LFS's RO unit is for some reason malfunctioning.
 

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Let me guess your LFS has more saltwater tanks than fresh?

I would except that from a mostly saltwater shop that doesn't
replace there cartridges when the should since normally only
the saltwater people would know how to check that stuff.

- Brad
 

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GEEK
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664 Posts
Discussion Starter · #7 ·
Let me guess your LFS has more saltwater tanks than fresh?

I would except that from a mostly saltwater shop that doesn't
replace there cartridges when the should since normally only
the saltwater people would know how to check that stuff.

- Brad
You are somewhat right. They are split in half between saltwater and freshwater, and do not sell any significant amount of plants, but they do seem to cater more towards the saltwater crowd.

I don't understand that second part of your reply, referring to "only the saltwater people would know how to check that stuff."

Thank you for your input.
 

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Just that the majority of there freshwater customers are mainstream consumers without your knowledge level on aquarium keeping let alone plants so they can fudge on things like RO water as it's probably still allot better than what they have in there tanks at home. The average light hobbyist only does one WC per three months and that's not going to be a good El Natural setup.

Everyone on this forum is above the learning curve compared to the mom or pop that comes in once every six months or so to buy little Johny a new Betta or guppy because it died again.

The sad part is people like us make bad customers for LFS's as we rarely need the extra services or new fish that the mainstream consumer needs on a regular bases. I've been making a point to stop at my LFS once a month to buy something little that I don't really need (food, prime, etc) but I'll never buy high margin items from them like tanks and filters since I know how to get better deals.

- Brad
 

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Thank you for the explanation. I checked the values out of my tap this morning and the values I got were:

pH: 7.6
GH: 7
KH: 4

The water supply to my home is the same as the LFS. Assuming a 75% reduction of mineral content with a functioning RO unit, I would still have expected lower values in the RO water that I purchased.

I would like to give the benefit of the doubt that the LFS's RO unit is for some reason malfunctioning.

It's also possible they have a different water source. Your home may be getting lake water with low mineral content and the fish store may be getting well water with a high mineral content. Either way you should probably let them know their water isn't very pure.
 
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