DI water vs/ RO/DI water

reefermadness31 · Mar 27, 2020

I'm new to saltwater and was curious about purchasing an RO/DI system vs using DI water to make saltwater. I work in a lab and have access to DI water out of a tap which is used to test trace elements etc. Is this water fine to use vs the RO/DI? I have been using it to top off my tank and seems to be fine there. It's a 24g and i have been purchasing from the lfs, but thats 25 minutes away and 2$ a gallon, so that might get old pretty quick.

Natescorals · Mar 27, 2020

You have been using RODI?

reefermadness31 · Mar 27, 2020

I used purchased RODI water to start my tank and for water change. I have been topping off with DI water from my work. I dont think it is reverse osmosis De-Ionized water though.

Natescorals · Mar 27, 2020

Do you have TDS meter to test the water? Also test for phosphates on the DI water just to be safe

Natescorals · Mar 27, 2020

Better to be safe than sorry. I used to purchase RODI water from my LFS and I almost lost all my livestock because their water was so dirty TDS read 80

Natescorals · Mar 27, 2020

After that I immediately bought my own RODI unit. Haven’t seen the corals grow and this happy ever since

Natescorals · Mar 27, 2020

Never ever ever trust your local fish store! Trust yourself!!! Everything your LFS does you can do better.

xxkenny90xx · Mar 27, 2020

Your di water is probably great if your using it in a lab. But like others have said, test it first! Also, I bought rodi water from my lfs once in a pinch and it ended up testing worse than my tap water, had to throw it out.

reefermadness31 · Mar 27, 2020

Oh wow, I didnt even think to test the purchased water. I guess i just assumed it was the best. Probably ignorant to think that. I'm assuming our DI water doesn't have phosphates since we actually test for phosphorus in some samples. What would be a good phophate level? any suggestions for a TDS meter? I cant imagine our DI water is dirty at all though.

PatW · Mar 27, 2020

Well, it depends. Back when I worked in labs, they often had distilled water taps. The labs had distilled water to suit THEIR purposes and not the purpose of a person in the salt water aquarium hobby. Distilled water often has copper contamination. And copper is catastrophic for marine invertebrates.

So what are they using the DI for? If it is just to wash glassware and make up solutions that are good enough, it might not work for you.

Also often these kinds of things are run and maintained by a technician with little over sight. They might be conscientious and they might not. They might know their stuff and maybe not. Even if they pass the first two, they might not get the resources to do a good job. Right now, you are trusting the label on a tap and that is not a good thing.

At the very least, you might try to do some checking to see if the system is up to snuff.

reefermadness31 · Mar 27, 2020

Well I actually work in the lab. We test for Copper and use the water in testing for low amounts of copper in product, so the water needs to be absent of minerals. We also run "blanks" whenever we test to make sure there is no contamination. There never is. It is De-Ionized water not distilled.

Waynerock · Mar 27, 2020

Natescorals said:
Better to be safe than sorry. I used to purchase RODI water from my LFS and I almost lost all my livestock because their water was so dirty TDS read 80

holy moly I get 32 out of my tap!!

Natescorals · Mar 28, 2020

Waynerock said:
holy moly I get 32 out of my tap!!

Not bad at all compared to some other cities. Just get a basic RODI system. Your tap water should become pristine! Just hook it up to your kitchen or bathroom sink