The most important thing an RO/DI will remove?

Whats the number one reason for an RO/DI system? Is it phosphates?
I tested my tap water and I tested my tank water and it comes out as 0 phosphates.

 

A lot depends on where you live and what is in your water source. Three other common things that are fine for drinking but are not fine for a reef tank because they will cause algae. Iron, nitrites, and nitrates.

There are many other things which water treatment plants get down to manageable levels according to govt standards. We can drink small amounts of these. Unfortunately, an aquarium is a semi-enclosed system (depending on filtration, water changes, etc). There's been many arguments as to how much of this stays in your tank and accumulates as a result.

You can obtain a water report from your supplier to see what is in your tap water. (Keep in mind that these levels are from that particular day the test was done. These figures change all of the time and that's why they regularly test and the results will change regularly too).

 

It's not one thing, but many different things. It also depends on whether you have a well or public water. If you have a well, you can have nitrates, nitrites, phosphates, iron, arsenic, ammonia etc. Even public water can have dissolved solids, heavy metals and additives. Flouride is added to most public water systems and many have nitrates and phosphates among others.

 

#1 thing RO/DI does for you is give you pure, clean water to go into our precious closed glass boxes we keep our delicate water dwelling creatures in. ;D

+ peace of mind!

TJ

 

Herbicides, pesticides, volatiles like fuel byproducts, endocrine disruptors, nitrates, silicates, copper, arsenic and many many others just to name a few. Consistency is the reason to use RO/DI, you get the same consistent water quality every time with a properly maintained system.