What are the differences?

I just wanted to know if you all could explain to me what the MAJOR difference between the water that results from say a Brita-type filter and water that is RO/DI filtered. I understand the major differences between the two filters (Brita is basically just an activated carbon filter and I understand RO/DI) but is there a major difference between the resulting water? If my tap water is pretty low in total dissolved solids, wouldn't a Brita or Pur filter remove any chlorine, etc? Just curious and trying to quench my thirst to learn more.

Adam

 

A brita is just carbon filtering.

 

Thanks Urban. I guess what I mean is what does a RO/DI filter remove that a carbon (Brita, Pur) filter doesn't? I understand that it filters finer particles but for decent tap water to begin with, does it make that big of a difference?

Adam

 

Divecj5, If you were to test your tap water you will see that there are many unwanted levels. One being Nitrates, Phosphates and then your undesolved solids.

Check your water and post your results.

 

If you can get a water quality report from your water company, you'll have an idea of what else an r.o./d.i. unit removes. Here's the report from my local company just to give you an idea:

http://www.themdc.com/watertable.htm

 

I'm glad I hit preview before posting. Joe and Annick hit the nail on the head...I'm just a slow typer.

Carbon removes Chlorine (a good thing since it will kill your tank). If your water company uses Chloramines (as most do now) as opposed to Chlorine, then the Chlorine will be blocked but the associated Ammonia will go into your tank. Depending on your biofilter, this may do little other than stressing your inhabitants, or it might be enough to kill your tank...it all depends on your system and your water source. Carbon does not remove Nitrites, Nitrates, phosphorus compounds, sulphates/sulphides, heavy metals, etc.

RO units remove most of the nasties but let let one real bad nasty right through...phosphates (AKA algae fertilizer). If you add a DI unit to your RO unit to remove the phosphates, then you are talking about real good water.

I won't give you a blanket answer here. Some people are blessed with amazing water. I would kill for the TDS that some of my friends in Seattle and Reno get. In St. Louis, I average 325 TDS but I've seen it occassionally as high as 425. One of my friends in Indianapolis would kill to get 425.

The key is to test your water for the known nasties and obtain a water report from your water district. They have to give it to you for free by law.

 

Wow...thanks for all of the explanations. I had a pretty good idea what the major differences were between carbon and ro/di filter systems, I just didn't really know what was passed through a carbon filter and what was filtered out in a RO/DI. I also didn't really know that phosphate was not filtered in RO but was with the DI attached. Great info. to know since I'm still in the "equipment and toys" phase of planning. I thought that I was pretty close funds-wise but just like another one of my hobbies (SCUBA diving), things add up quick.

Thanks for the advice and info. Karma to all