RO Filtered Well Water

[arbiter42]

Hi all,

Recently moved into a new house with well water and about to start setting up a big (~200 gallon) tank. Because of high arsenic in the well water we have an RO filter running before the tap, and I'm curious if it would be viable to use the RO filtered tap water for mixing. Below is a screenshot of the results of our pre-filter water test (mandated by the state), and nothing except obviously the arsenic jumps out to me as risky. The current TDS in the tap water is about 60ppm (that's after the existing RO filter).

I have a 4-stage RO/DI filter (BRS), and so my main objection to using it is just the wasted water. This is obviously not a huge deal because well water is free, but I like to minimize waste where I can, and also I'd like to better understand what I'm doing these steps for.

Basically what I'd like to know is:
a) what are some risks to using the filtered tap water? (is the main one just "mystery local bacteria"?)
b) are there mitigation solutions besides using an additional RO/DI filter? (e.g., beneficial bacteria, more CUC, etc.)
c) ...other thoughts about this situation that aren't the rule of thumb "always use RO/DI, 0TDS water" (I am aware of the rule and would like to understand the "why" better)

Thanks in advance to anyone who can advise!

 

[Saltyreef]

Hi all,

Recently moved into a new house with well water and about to start setting up a big (~200 gallon) tank. Because of high arsenic in the well water we have an RO filter running before the tap, and I'm curious if it would be viable to use the RO filtered tap water for mixing. Below is a screenshot of the results of our pre-filter water test (mandated by the state), and nothing except obviously the arsenic jumps out to me as risky. The current TDS in the tap water is about 60ppm (that's after the existing RO filter).

I have a 4-stage RO/DI filter (BRS), and so my main objection to using it is just the wasted water. This is obviously not a huge deal because well water is free, but I like to minimize waste where I can, and also I'd like to better understand what I'm doing these steps for.

Basically what I'd like to know is:
a) what are some risks to using the filtered tap water? (is the main one just "mystery local bacteria"?)
b) are there mitigation solutions besides using an additional RO/DI filter? (e.g., beneficial bacteria, more CUC, etc.)
c) ...other thoughts about this situation that aren't the rule of thumb "always use RO/DI, 0TDS water" (I am aware of the rule and would like to understand the "why" better)

Thanks in advance to anyone who can advise!

In general its always good to use a 0TDS water to negate any additional build up of minerals that is un needed aside from the salt you mix in.

Since we dose so many elements into the water with the addition of salts and have a limited range of acceptability, this is why you dont see many experienced reefers relying on tap water or RO minus DI. Though the latter is much more preffered.

 

[alton]

PM Russ at Buckeye and he will help you out

 

[arbiter42]

In general its always good to use a 0TDS water to negate any additional build up of minerals that is un needed aside from the salt you mix in.

Since we dose so many elements into the water with the addition of salts and have a limited range of acceptability, this is why you dont see many experienced reefers relying on tap water or RO minus DI. Though the latter is much more preffered.

So you'd say, roughly, "minerals (and other stuff) you can't account for"? Makes sense, and sort of lines up with my thinking that I'm just making my life harder if I'm adding in unknowns. I've been doing RODI for so long with other tanks due to chlorinated +/or heavy-metaled city tap water that this is just not a line of thought I'd gone down.

 

[Saltyreef]

So you'd say, roughly, "minerals (and other stuff) you can't account for"? Makes sense, and sort of lines up with my thinking that I'm just making my life harder if I'm adding in unknowns. I've been doing RODI for so long with other tanks due to chlorinated +/or heavy-metaled city tap water that this is just not a line of thought I'd gone down.

Yep!
If theres TDS, there are still dissolved solids and 100% make it harder to dose or mix accurately based on test results.

Also, keep an eye on your resins if you follow through with deionizing as well water usually has an excess amount of dissolved c02 which will destroy the resins in a short bit.

Negate this by aerating your RO before pumping it through the resins.

 

[arbiter42]

Yep!
If theres TDS, there are still dissolved solids and 100% make it harder to dose or mix accurately based on test results.

Also, keep an eye on your resins if you follow through with deionizing as well water usually has an excess amount of dissolved c02 which will destroy the resins in a short bit.

Negate this by aerating your RO before pumping it through the resins.

Great advice, thanks!