Top off water to reduce alk?

[reefrider]

have been having high alk readings ~5 and dKh ~ 14. Should i just top off with fresh ro/di water. I won't be adding buffer.

[antbreon]

you can add a little white vinegar..just a cap full for about 30 gal..will reduce you alk.

[reefrider]

if i did that i am worried about shocking the system. i would rather let it naturally drop off. just not sure about the top off water. thanks for the vinegar suggestion

[bertoni]

Vinegar won't drop the alkalinity for very long. It binds alkalinity temporarily until bacteria consume the organic acid, but that's typically only hours in a tank. Water changes can lower alkalinity safely, but if you stop dosing all forms of alkalinity, the level should drop on its own fairly rapidly.

Some of the less obvious sources are pH buffers (they all add alkalinity, despite any advertizing) and tap water.

[Randy Holmes-Farley]

Yes, stopping or reducing the addition of buffers is the obvious answer.

Were you previously adding buffers in your RO/DI water?

Pure fresh water additions won't reduce alkalinity except if you stop adding something else that you were previously adding to that RO/DI. :)

[reefrider]

i was adding CaribSea Buffer plus.

[Randy Holmes-Farley]

OK, just stop that for a bit then add less when you are supplementing it, based on alkalinity measurements. :)

Just so you understand, it may be convenient to use the RO/DI as a vehicle for adding needed supplements, but RO/DI does not "need" any buffering so don't add anything to it unless you know the tank water needs it.

[reefrider]

thanks Randy for the insight. I would add buffer to increase pH from 7 to 8.2? is that not correct?

[shifty51008]

are you tring to buffer the top off water? don't buffer top off water, when it goes into the tank your water will get mixed very quickly and buffer itself, all that buffer is doing is raising your alk.

[disc1]

thanks Randy for the insight. I would add buffer to increase pH from 7 to 8.2? is that not correct?

No, that's not correct. The pH of your top off water has absolutely zero effect on the pH in the tank.

[Randy Holmes-Farley]

Right, it is not correct. Never add buffers to attain a specific pH, either in the aquarium or in the RO/DI. Only to boost alkalinity.

If you want a pH boost WHEN you need to add alkalinity, use a high pH additive like baked baking soda or limewater. :)

[reefrider]

thanks a lot. makes sense now. Probably should have listen better when i took marine chem in college...

[Randy Holmes-Farley]

:lol:

These may be useful:

The “How To” Guide to Reef Aquarium Chemistry for Beginners, Part 1: The Salt Water Itself
http://reefkeeping.com/issues/2007-03/rhf/index.php

The “How To” Guide to Reef Aquarium Chemistry for Beginners, Part 2: What Chemicals Must be Supplemented
http://reefkeeping.com/issues/2007-04/rhf/index.php

The "How To" Guide to Reef Aquarium Chemistry for Beginners, Part 3: pH
http://reefkeeping.com/issues/2007-05/rhf/index.php

The “How To” Guide to Reef Aquarium Chemistry for Beginners,
Part 4: What Chemicals May Detrimentally Accumulate
http://reefkeeping.com/issues/2007-09/rhf/index.php