Dosing vinegar every 2 hours or once a day?
 

I am dosing about 20 ml of vinegar for 65 gal tank over 24 hours. I have been pretty happy with the results for a while.

While trying to fine tune my Ph, I am little concerned about dosing vinegar at night. With my dosing pumps, I have two options ... spread the dosing over 24 hrs (including night) or dose all at once.

What is better?

In general spreading any dosing out over a 24 hour period is usually better
If you have the ability do it. If not don't worry

But what about dosing vinegar at night? The bacteria does not need it without light and it raises the Ph.

Vinegar is an acid, so it will lower the pH. As it is consumed by bacteria, the pH will rise though, and aeration will help, too, by bringing carbon dioxide into the tank to counteract the "consumption" of carbon dioxide by the H⁺ ions from the vinegar.

My understanding is that the bacteria will not consume it during the dark hours - only during the light. So if I am adding vinegar also during the night, I am lowering the Ph the whole night. Bacteria will then work on it during the light period and raise it back up.

The above is the reason I started this thread. It would be the best to spread the dosing throughout the "light time" only and have the bacteria consume it right the way. The problem I have is that my doser can do only one or the other (spread it over 24 hrs or do all of it at once).

I plan to switch from dosing 24 hrs to dosing just once at the start of my light period. I will use Apex probe to graph it and I will get back with my results.

now some one correct me if I'm wrong here, but aerobic and anaerobic bacteria will operate light or dark, unless your talking something photosynthetic the bacteria doesn't care if the lights are on.

I got the information that they are non photosynthetic from the following thread:

http://www.reefcentral.com/forums/sh...+carbon+dosing

Also attached is a typical Ph graph in my tank over 24 hours dosing 1ml every 2 hours. The graph starts with my lights on for 8 hours.

The bacteria bloom encouraged by carbon dosing consumes 02. Generally speaking photosynthetic organisms release O2 in the lighted period. So generally the carbon source is added in the lighted period when O2 is the highest.

That said, I add a small amount of vinegar hourly, 24/7. The low dose doesn't cause a big bloom so O2 isn't an issue.

Dosing vinegar does lower the pH a bit, depending on the size of the dose, but the bacteria can consume it light or dark, so I think adding it most likely is okay at any convenient time. Large doses might need to be broken up, though. I might measure the pH after an addition to see what's happening, and work from there.

Here are my experiment results (ran it for 2 cycles):

Dosing only once a day at the start of the light period spikes the Ph by less then 0.1 when added at once. The spike lasts 30 minutes. Not adding any vinegar from then on, specially not at night, makes no other difference to the overall Ph curve or the range.

So if the dosing at night makes no difference at my regular rate (20 ml per day for my 65 gal), I am going back to spreading the dosing over the 24 hours to avoid the small spike when dosing only once a day.

That sounds like a good plan to me. :) Good luck!