During the past 6 years I have gathered a lot of knowledge on maintaining a healthy reef aquarium. Now I need
to stress this loudly and clearly: I am NOT a marine biologist. I am NOT a chemist. I am NOT a professional
aquarist. And my reef aquarium is by no means as impressive as the ReefCentral
TOTM tanks. But I have kept my reef aquarium inhabitants happy for several years. I do know a lot of
rights from wrongs. And that is mostly due to the wonderful people at ReefCentral, several books I have read
on the subject coupled with my own experiences and my basic (first year university) knowledge of chemistry.
Below find a list of commonly asked questions that I have aggregated. I hope this can be helpful to other
people as I had to spend a lot of time and energy to figure some of this out. It is no substitute for
experience but some things are better learnt through theoretical means than through failure as we are
working with live animals.
Question How do I raise the pH in my tank?
pH is dependent on many factors, and as this is not a lesson in chemistry here are the
three major factors you need to address.
The first is to ensure your alkalinity is at the right level. Ideal alkalinity is between 7dKH and
11dKH. If your alkalinity is much below 7dKH, it wont be able to buffer your pH. Therefore your pH will
fluctuate much more than it would have had your alkalinity been higher. Once your alkalinity is in the
right range, ensure the room where your aquarium is situated is adequately ventilated.
CO2 in the air dissolves in the aquarium and as it is acidic, it will lower the pH of the
aquarium. Since we exhale CO2, the CO2 content in the house will be much higher
than the outside CO2 levels. By ventilating the room and therefore equalizing the air with
the air outside, the CO2 levels will be lower and should closely match the outside.
Lastly, ensure your tank has good aeration. It does not help if you lower the CO2 content and
the CO2 vs O2 ratio is correct, but you do not have enough surface agitation to
properly pull in O2 from the surrounding air. The three best methods for proper aeration are
surface overflows, pointing your power heads towards the surface of the tank (and also having a large
surface area to volume ratio), and using a good skimmer.
Please do not use off the shelf pH chemicals to try and raise your pH. Except for raising alkalinity,
one cannot directly control your pH. pH is controlled indirectly via the three methods above.
Question How do I dose alkalinity supplement?
The most important issues to remember are:
Never dose alkalinity supplements together with calcium supplements. When you dose them at the same time
the alkalinity and calcium reacts and you will have a precipitation of Calcium Carbonates - it will look
like snow flakes falling to the bottom of the sump. Rather add alkalinity first, then after a couple of
hours add the calcium supplement.
Never add so much alkalinity supplement that the immediate effect on your pH is more than plus or minus
Question I am dosing alkalinity/calcium but I am struggling to raise it to where I want it.
Ensure your magnesium levels are correct. It should be in the 1300mg/L to 1500mg/L
range. If it is too low, you will not be able to maintain proper alkalinity/calcium levels.