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Discussion Starter #1
Just wondering if any folks out there mix their water in a reservoir like a rubbermaid trashcan or something like that.

I plan on doing this with RO plus my KH/GH ingredients.

One little complication is that after a water change there's a little less than half the water still in the reservoir (trashcan). So now I am faced with filling it back up with RO, but now I don't really know how much water volume I just put back in, after all it's a trashcan not a measuring cup. That means that now I am not sure how much of my GH/KH ingredients to add back so I can get the same GH/KH that I just pumped into my tank. I don't want those values bouncing around and stressing my fish/plants.

Anyone have any strategies for this? I thought of maybe using a TDS meter to find out my target TDS after I reach my goal GH of 5 and KH of 3. That way I can just aim for that instead of worrying about water volumes. Of course I'd have to target TDS after addition of KH and TDS after addition of GH.

Another option is to leave the reservoir full of pure RO and dose KH (sodium bicarb) and GH (Barr GH Booster) straight to the tank after water change. My only concern there is the sudden but brief change in KH and consequently PH. I don't know if that would stress the fish and/or plants or not.
 

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Hi banderbe,

I mix my RO in a 33gal rubbermaid for weekly water changes. First, you could only make the amount of water needed for one water change. I have all my reconstitution chem's premeasured and determined for the 33 gal. can and drain my tank down to a predetemined mark on the tank and use the entire reservoir.

The other option for making more RO water than for a single water change would be to put gal. (1, 2, 5, etc.) increments with a permament marker on your mixing container, or a premarked dipping stick. After your water change determine how much RO your putting back in to fill it back up. If you re-calculate your soda, mg, etc. to reach your targets on a per gallon basis (or any preferred unit) you can multiply it up to the amount of new RO water you use to fill it back up. You just have to keep track of it, especially if it varies weekly.

I use a gram scale to measure everything out and can get pretty accurate (.01 gr.) with my measures. I don't think a TDS would give you all the necessary info to keep track of all the individual ratio's (mg, Ca, soda, KH, GH, etc.) as all molecules are factored into TDS condictivity not just the one's which make up GH and KH respectively.

Hope this helps...Don
 

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Discussion Starter #3
Don135 said:
Hi banderbe,

I mix my RO in a 33gal rubbermaid for weekly water changes. First, you could only make the amount of water needed for one water change. I have all my reconstitution chem's premeasured and determined for the 33 gal. can and drain my tank down to a predetemined mark on the tank and use the entire reservoir.

The other option for making more RO water than for a single water change would be to put gal. (1, 2, 5, etc.) increments with a permament marker on your mixing container, or a premarked dipping stick. After your water change determine how much RO your putting back in to fill it back up. If you re-calculate your soda, mg, etc. to reach your targets on a per gallon basis (or any preferred unit) you can multiply it up to the amount of new RO water you use to fill it back up. You just have to keep track of it, especially if it varies weekly.

I use a gram scale to measure everything out and can get pretty accurate (.01 gr.) with my measures. I don't think a TDS would give you all the necessary info to keep track of all the individual ratio's (mg, Ca, soda, KH, GH, etc.) as all molecules are factored into TDS condictivity not just the one's which make up GH and KH respectively.

Hope this helps...Don

Thanks Don those are some good ideas.

I guess my idea with TDS is that starting from RO water with TDS 0, I add GH until I get my desired level, then measure TDS and write that down.

Next, I would add KH until reaching desired level, then measure TDS and write that down.

Now I know the TDS values for this volume of water at point 1 and point 2. My theory is that once I do a water change and have say, 2/3 the volume in the tank, I can fill it back up with RO, the TDS will then drop, then I can add GH and KH again until I hit both of the values recorded previously.

Maybe that wouldn't work though.. I have thought more on this and I think it's probably easier to just dose GH and KH straight into the tank during water change. It's a smaller volume of water that is the same every time.
 

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put gal. (1, 2, 5, etc.) increments with a permament marker on your mixing container, or a premarked dipping stick.
I'd also suggest this. Seems to be the easiest, cheapest way!
 
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