Using RO waste water for fw planted aquarium?

[drfu]

So after all the research that i have done i decided to order cpdi90mf for my reef systems vs buying ro water, I'm really looking forward to getting it next week! The one question i have right now with it is this:

Can i use the waste water for my freshwater tank?

I have googled this and have read everything from "sure i do", to "no too much tds" and everywhere in the middle.

If the waste water has no chlorine, chloramine, ammonia, nitrites or nitrates in it just minerals should this not be good enough for a freshwater planted system?

Or am i totally wrong with this and the pre filters don't remove these and the amount of tds coming out of the membrane are way too high for the fish/plants? My freshwater system is just your standard variety of plants & community freshwater tropicals.

I have read that using the clean rodi water is no good for fw tanks as it has all of the good minerals, trace elements and you would have to buy a bunch of supplements to make it safe. If this were the case i would just stick to using tap water & Prime.

Everyones thoughts on this would be great, thx in advance!

[Mebbid]

My first thought about this is that its a bad idea. The water will have concentrated levels of everything in it including heavy metals.

It could work but it really depends on the water source.

[drfu]

Originally Posted by Mebbid

My first thought about this is that its a bad idea. The water will have concentrated levels of everything in it including heavy metals.

It could work but it really depends on the water source.

Once i get the init installed i will check the tds of both then

[Grumble69]

It'll depend on what the water initially has in it + how efficient your RO system is. My undersink RO unit produces around 5 gallons of waste for every 1 gallon of RO. So my "waste" has about 20% more minerals. If your water is not overly hard, that might be just fine.

Now I believe I remember seeing some RO units that use high pressure and they make 1 gallon of waste to 1 gallon of RO. ...that probably would work so well.

[drfu]

So i just installed it, have it set to 3:1 ratio, did a hardness test with the strips SpectraPure sent along with it and its one of those stupid color strips, if i were to guess my hardness is between 50-120 gph or between 3-7 dh

[Grumble69]

If it's 7, then the waste would push it up to 9-10 which would be just fine.

[drfu]

I just did a test of the waste water and the strip says 25? I have color test strips! So I guess i need to buy a gph test kit and a tds meter before trying?

[Sk3lly]

I have a RO/DI unit myself. I make up a container of 3 parts RODI and one part waste water. The waste water helps to remineralise my RODI

Remember the waste water only becomes waste at the RO membrane. So at this stage it has gone through two maybe 3 fine grade filters depending on your system. So the larger particles of tds should have been filtered out. This waste water will still contain chlorine and chloramine as it hasn't gone through the stage that removes them. Get yourself a tds meter rigged up.

[manbeast]

Here's a good start
HM Digital DM-1 In-Line Dual TDS Monitor, 0-9990 ppm Range, +/- 2% Readout Accuracy by HM Digital http://www.amazon.com/dp/B001EHAZGW/..._uSnttb00KT6CR

[drfu]

Originally Posted by manbeast

Here's a good start
HM Digital DM-1 In-Line Dual TDS Monitor, 0-9990 ppm Range, +/- 2% Readout Accuracy by HM Digital http://www.amazon.com/dp/B001EHAZGW/..._uSnttb00KT6CR

This came with my SpectraPure, i guess it measures what is going into the membrane & what is coming out of it but from what i understand it doesn't measure what would be coming out of for waste water, that is why i think i need a portable one. The portable one wont tell me what kind of tds i would be putting in my tank vut at least i would know how much and if its safe to do so. Also if i measure Ph, kh & gh i should have a good idea if i should use waste or not. I like the idea of maybe mixing good DI with the waste RO as Sk3 said.

[BillD]

Originally Posted by Sk3lly

I have a RO/DI unit myself. I make up a container of 3 parts RODI and one part waste water. The waste water helps to remineralise my RODI

Remember the waste water only becomes waste at the RO membrane. So at this stage it has gone through two maybe 3 fine grade filters depending on your system. So the larger particles of tds should have been filtered out. This waste water will still contain chlorine and chloramine as it hasn't gone through the stage that removes them. Get yourself a tds meter rigged up.

This seems contrary to my understanding of how an RO unit works. The chlorine is supposed to be removed before the water hits the membrane to prevent damage to the membrane. As well, the particle filters that are ahead of the RO membrane will not reduce the TDS as the minerals are dissolved, not particulate.

[drfu]

Originally Posted by BillD

This seems contrary to my understanding of how an RO unit works. The chlorine is supposed to be removed before the water hits the membrane to prevent damage to the membrane. As well, the particle filters that are ahead of the RO membrane will not reduce the TDS as the minerals are dissolved, not particulate.

So are you saying that their is no reason to use Prime on my waste water and i should not have to do a mix of good & bad?

[drfu]

Originally Posted by Mebbid

My first thought about this is that its a bad idea. The water will have concentrated levels of everything in it including heavy metals.

It could work but it really depends on the water source.

So i have tested my waste water with my @&$%# API freshwater test kits & here are the results:

TDS 220 (tap water was 200)
Ph 7.4 - 7-8
Kh 7dKh or 126 ppm
Ammonia could be as high as .25 ppm but i can not tell for sure??
Phosphates .25 ppm
Copper, nitrites, nitrates are not detectable

[drfu]

I got a gh test kit today, my waste water measures around 8-10 dGh, is this a bit high for tetras, corys, standard community fish & plants?