Rodi waste water to top off live rock tank

miserkris

miserkris

New member
Hi
I have a 10g tank with sw , liverock and a hardy damsel for a long time.Been using rodi for top off.

Can I use RO waste water for topping off?It's kinda like a fowlr. It won't have chlorine right...would it hurt ?
TiA
Kris
 
Kinda defeats the purpose of using RO water for your regular tank volume doesn't it? At that point, why would you use RO for anything?
 
miserkris said:
I use rodi for my main DT.

Will rodi waste water affect live rock and a damsel?
Click to expand...

Yes, it is by definition the dirtiest water, it's what your filter pulls out of the water as it cleans it. I agree why waste your time filtering the water at all if you are going to pour all the pollutants back into your tank.
 
He is not topping his display tank off with the dirty water, just his liverock tank. I think it will be fine.

Its not like every place you get your liverock from is using rodi that would be crazy. Most places I know just use hose water or it comes from the ocean.
 
PirateLove said:
He is not topping his display tank off with the dirty water, just his liverock tank. I think it will be fine.

Its not like every place you get your liverock from is using rodi that would be crazy. Most places I know just use hose water or it comes from the ocean.
Click to expand...
Exactly...My point. Just wonder if it'll affect the life in rock and that velvet sob damsel....lol.
 
Your rodi waste water isn't the dirtiest water. It has passed through the sediment filter and the carbon block. So the things that those remove have been taken out of it, like sediment and chlorine. This is important to preserve the ro membrane, it's very delicate. So those prefilters take out some bad stuff, and then the water is pushed across the film of the ro. Most of the tds in your water will pass by the ro, as intended, and the few that get through it are sopped up by the di resin.

The waste water is carrying those extra tds, but it has been prefiltered though low-micron sediment filter and carbon. So it's not dirtier that tap water, it's just dirty in a diff way. It's comparable to what you would get using a Brita filter, if you had wicked dirty water to start with.
 
thegrun said:
Yes, it is by definition the dirtiest water, it's what your filter pulls out of the water as it cleans it. I agree why waste your time filtering the water at all if you are going to pour all the pollutants back into your tank.
Click to expand...

Not exactly true... see below.

CStrickland said:
Your rodi waste water isn't the dirtiest water. It has passed through the sediment filter and the carbon block. So the things that those remove have been taken out of it, like sediment and chlorine. This is important to preserve the ro membrane, it's very delicate. So those prefilters take out some bad stuff, and then the water is pushed across the film of the ro. Most of the tds in your water will pass by the ro, as intended, and the few that get through it are sopped up by the di resin.

The waste water is carrying those extra tds, but it has been prefiltered though low-micron sediment filter and carbon. So it's not dirtier that tap water, it's just dirty in a diff way. It's comparable to what you would get using a Brita filter, if you had wicked dirty water to start with.
Click to expand...

My RO/DI "reject' water (it's not waste water to me) is cleaner than my tap water and my RO/DI system is giving me zero TDS. I use the reject water to do laundry.

But to the OP's question, it's just a 10g tank, use RO/DI and avoid any potential issues with contaminating your LR.
 
roberthu526 said:
Just think about it: whatever is filtered out is in that waste water. It is worse than plain tap water...
Click to expand...

Just think about it: water that has not passed through a sediment filter and carbon block (tap water) is not cleaner than water that has (waste). That's why you have to replace the sediment and carbon, they capture stuff from the water and get full over time. That stuff is removed before the water passes the ro membrane to become waste.

If what you're saying is true, and whatever is filtered out goes down the drain as waste, what are the prefilters even doing, why do they get full, and why do we change them?
 
The tds in my waste water is higher than the tds in my tap water. Regardless, why would you want to soak rock in water that is anything but the best? It is going to absorb whatever you place it in, seems like a silly corner to cut that has a good chance of causing issues down the road. If the cost of 30 gallons of quality saltwater is too high of an expense, respectfully this is likely not a good hobby for you.
 
CStrickland said:
Just think about it: water that has not passed through a sediment filter and carbon block (tap water) is not cleaner than water that has (waste). That's why you have to replace the sediment and carbon, they capture stuff from the water and get full over time. That stuff is removed before the water passes the ro membrane to become waste.

If what you're saying is true, and whatever is filtered out goes down the drain as waste, what are the prefilters even doing, why do they get full, and why do we change them?
Click to expand...

I think was he was meaning was the amount of filtered impurities gets piled up and as the water gets moved along but the filtered part stays behind it just keeps accumulating so when you have waste water it has higher concentrations of impurities than what you started with.

Just my thoughts on it
 
It is a mistake to confuse TDS with purity. High TDS isn't the same as dirty, and low TDS isn't the same as clean.
Since TDS meters are often used to test water "purity," it is important to understand what they do not detect. As conductivity meters in disguise, TDS meters will only detect mobile charged ions. They will not detect any neutral (uncharged) compounds. Such compounds include sugar, alcohol, many organics (including many pesticides and their residues), and unionized forms of silica, ammonia, and carbon dioxide. These meters also do not detect macroscopic particulates, as those are too large to move in the electric fields applied. So if you see "rusty" looking water from iron oxide particulates, that won't be measured. Neither will anything else that makes the water look cloudy. Bacteria and viruses also won't be detected.

Consequently, the term "total dissolved solids" is really quite a misnomer. "Total charged ions" is likely a much better term for what it measures. Fortunately, a measurement of total charged ions is good enough for many aquarium purposes.
Click to expand...
http://reefkeeping.com/issues/2004-04/rhf/feature/index.php

In any case, there are several things happening in a rodi unti to clean the water.
The sediment filter, typically a foam block, removes particles from the water. Its purpose is to prevent clogging of the carbon block and RO membrane. Good sediment filters will remove particles down to one micron or smaller.

The carbon, typically a block of powdered activated carbon, filters out smaller particles (ideally down to 1/2 micron or smaller), adsorbs some dissolved compounds, and deactivates chlorine. The latter is the most important part: free chlorine in the water will destroy the RO membrane.

The RO membrane is a semi-permeable thin film. Water under pressure is forced through it. Molecules larger/heavier than water (which is very small/light) penetrate the membrane less easily and tend to be left behind.

The DI resin exchanges the remaining ions, removing them from the solution.
Click to expand...
http://www.reefcentral.com/index.php/rodi-faq

The waste water is water that did not pass the membrane. As such, it has been filtered for sediment, and by carbon. In this way it is cleaner than tap water.

Because some of the water has gone through the membrane, the waste water is more concentrated in the stuff that membranes remove. It also has not been through a di. In these ways it is dirtier than the product water.

IDK how you would know if it is safe for your fowlr. Plenty of people use treated tap water for fowlrs. If chlorine were the only concern that would be one thing, but there's other stuff in there too. IDK what all might get removed by the membrane and di that could hurt a damsel, if anything. It's not that diff from asking if you can run this tank on dechlorinated tap-water, but instead of using drops, your using the carbon on your rodi to dechlor it. If you do it I wouldn't plan on ever using the rock in a coral tank, I'm pretty sure it's the DI resin that removes copper.
 
thegrun said:
The tds in my waste water is higher than the tds in my tap water. Regardless, why would you want to soak rock in water that is anything but the best? It is going to absorb whatever you place it in, seems like a silly corner to cut that has a good chance of causing issues down the road. If the cost of 30 gallons of quality saltwater is too high of an expense, respectfully this is likely not a good hobby for you.
Click to expand...

I agree.
 
Just stick the waste water tube into your top loading washing machine and gentle close the lid - "free" washer fill up. Helps if you synchronize laundry day with DI-water-making-day.
 
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