Ro/di

[patryuji]

...
I never gave it a second thought until someone mentioned not to use it for FW; the I went looking to validate the statement. So, no it's not a science experiment, I don't want to 'play w/ my numbers.

However if you consider your time to be worth something I would wonder what the true cost benefit number is for the ro/di filter once you factor in dosing, testing, mixing time and costs. For FW it sure isn't filter the water - use the water as compared to using bottled water as I do now which is open the 5g jug and siphon in.
...And for the record, it was Bob Fenner over at wetwebmedia whose posting first recommended mixing the two first in this thread. Credit where credit is due

I was thinking that after the initial test phase you would have a percentage that should "hold true" for most cases with enough *accuracy* that you would not have to worry about stressing the life in your tank from a big change in water mineral content and pH.

I simply agreed that it sounded like a good idea to mix the two [not claiming credit for anything] but even better if a reputed/respected member of the aquarium community espouses such ideas.

 

[Ziggy953]

If you have been using straight tap water (dechlorinated of course) and you get an RO/DI unit, start using the RO/DI water to mix your SW with. The "mineral content and PH" are going to come from the salt mix you use. The point of RO/DI water is to remove nitrates, phosphates, hard metals and hundreds of other things that is in water out of the tap. I honestly don't see a benefit of "easing" into the transition from one source to the other. The sooner you have good source water the sooner you will have a more balanced tank with less chances of algae out breaks.

 

[tawolcott]

The discussion went another direction when I mentioned using for my FW too.. that's when it all crumbled, so to speak. BTW: Haven't been using tap, been using bottled since my area is high in silica and phos. Which is why is just po's me to consider mixing that in w/ the pure water I just paid to get rid of. I'm still trying to find out what the composition of the waste water is, since Bob over at wetwebmedia suggests mixing some of that in for FW (at a rate of 1/3 or 1/4). How 'clean' is the waste water? Are the contaminants in that. I tested the waste water vs the ro/di water. The nitrate level of the waste matched my tap (5-ish), and the ro/di was 0 which makes me think that if I use the waste I'm just dumping all that crap I paid to get rid of right back in the tank. Which will just drive me to drink (more)

 

[cmor1701d]

The waste water is probably higher in concentration for some minerals than straight tap. Waste is about 4 gallons for every gallon of RO. Soyes, mixing it back with RO water is adding some of that 'crap' back, though in a diluted state. If you only need it for high pH problems (limestone, etc.) then it's probably fine. If you have PO4 and nitrates and don't have a planted tank, then I'm not sure I would mix it.