RO/DI water chemistry

[korbynlehr]

I use RO/DI water for water changes with my reef crystals and also plain (no salt) for top offs.
The salt/RO mixture should not need anything like the b-ionic for calcium and alkilinity is this correct?
But my top off water does need to have this added is this correct?

[tonyscoots84]

wrong.. ur ro + salt = saltwater might have a diff. level in cal, alk and or magnesium... so i would adjust accordingly and test everything with a good quality test kit such as salifert (affordable to)...in ur top off water u can put either one alk or cal... me personally i dont bother i just do my 2 doses in the am and pm...

[Randy Holmes-Farley]

Neither the salt mix nor the evaporation replacement need anything added UNLESS:

1. You choose to use the top off as a way of delivering things that your tank needs. I choose to use top off as a way of supplying calcium and alkalinity to the tank, using limewater. But in general, top off water does not "need" to have anything added, and you should not try to measure or control the pH of the RO/DI water. Its pH is not important in terms of tank pH at all.

2. You are not happy with the parameters in the salt mix. I use Instant Ocean and I bump the calcium by 70 ppm with Dowflake and magnesium by 150 ppm with MAG flake (partly as a way to offset magnesium losses due to calcification).

These articles may help:

Reverse Osmosis/Deionization Systems to Purify Tap Water for Reef Aquaria
http://reefkeeping.com/issues/2005-05/rhf/index.htm

especially this section:
http://www.reefkeeping.com/issues/2005-05/rhf/index.php#8

and in general:

Reef Aquarium Water Parameters
http://www.reefkeeping.com/issues/2004-05/rhf/index.htm

[doesheya]

Randy,
We lose about 6-8 cups a day to evaporation. Are you saying I can put the b-ionic in with this top off water and it will be fine?

Thanks,

Mark

[Randy Holmes-Farley]

You can put one part in it, but not both.

[doesheya]

so I can either put part1(the calcium) or the part 2 in with the top off rodi water?
When would be a good time to add the other part?

[Randy Holmes-Farley]

I'd put the alkalinity part in it if you decided to go that route. The timing of the calcium addition does not matter.

[korbynlehr]

Is it okay for me to mix some of the alk with say half the top off then put it in the tank and mix the calcium with the other half top off andf put it in directly after the alk/top off?