I do use a skimmer, but the real secret for me is my Korallin S-1502 Sulphur Denitrator. It turns nitrates into nitrogen gas which simply rises out of the water column and thus exported out of the tank. Therefore my entire nitrogen cycle is maintenance-free...from ammonia to nitrogen gas and out the tank without any intervention on my part. A side-effect of denitrification is that it makes the water more acidic and thus lowers the pH, and for this reason the S-1502 also includes some aragonite in addition to the sulphur pellets, so as the water becomes more acidic it dissolves the aragonite and thus buffers the tank with kH and Ca.
This works well enough that I don't have to dose any Ca, but I do need to dose Alk every few days to keep it up in the 9's.
I just want to clarify that the denitrator does not actually add ANY alkalinity to the water. In fact, it is a net consumer of alkalinity in the sulfur denitration process.
Adding the aragonite to dissolve will help add back a portion of what was depleted, but not all of it.
That is why you do not need to add calcium (since it is added by the dissolving aragonite and not consumed by the denitrator), but still need to add alkalinity (because the denitrator overall is not actually adding any, but rather depleting it a bit, less so than if you did not use the aragonite, however).
FWIW, I discuss that in detail here:
Nitrate in the Reef Aquarium - REEFEDITION
from it:
Sulfur Denitrators
In these systems, bacteria use elemental sulfur and produce N2 from the sulfur and nitrate according the following equation (or something similar):
2 H2O + 5 S + 6 NO3- → 3 N2 + 5 SO42- + 4 H+
The production of acid (H+) in this reactor can tend to reduce the aquarium alkalinity. It has also been suggested to pass the effluent of such a reactor through a bed of aragonite to use the acid (H+) produced to dissolve the calcium carbonate, and thereby provide calcium and alkalinity to the aquarium. While that is a fine idea, it doesn’t add much calcium and alkalinity to most aquaria.
To estimate the magnitude of the effect, we start with a liberal estimate of how much nitrate might be removed. Say 10 ppm of nitrate per week.
10 ppm nitrate = 0.16 mmole/L of nitrate
Since 4 moles of H+ are produced for every 6 moles of nitrate consumed, this will produce
0.107 mmoles/L of H+ per week
How much calcium this could produce?
Assume that it takes one proton to dissolve one calcium carbonate:
CaCO3 + H+ → Ca2+ + HCO3-
Clearly, this is a substantial overestimate because much of the acid will be used up driving the pH down to the point where CaCO3 can even begin to dissolve. Consequently, we have an upside limit of 0.107 mmoles of Ca2+per week. Since calcium weighs 40 mg/mmol, that’s 4.3 ppm Ca2+ per week.
For comparison, an aquarist adding 2% of the tank volume in saturated limewater daily is adding on the order of 16 ppm of calcium per day. Consequently, this method may not be especially useful for maintaining calcium. Additionally, the acid produced will have a long term lowering effect on the alkalinity. In fact, it is double dipping on the alkalinity depletion since alkalinity is consumed when the nitrate is produced, and again when it is removed in the denitrator. So if you use a sulfur denitrator, be sure to monitor the alkalinity in the aquarium.
I just kind of made up a dosing scheduled taking the instructions into account i decided to do a little trial and error test for myself about how much to add daily and its going very well. i have been dosing it daily since late December i started off with 2ml per day and am now moving to 3ml because of more trial and error experiments involving raising my cal to 500 and alk to 12. i had heard the main reason you dont bring your alk numbers this high is because your coral skeleton with actually out grow the flesh of your acropora resulting in "burnt tips" so i am now dosing 3ml of essential elements and 6ml of coral vite daily to try to see if the flesh of the coral can keep up. i know its probably a little excessive but i like to play around with stuff alot and see what happens. i have had great coral growth my my reefer friends standards thus far so if it doesnt get noticable faster or corals look bad i will go back to what i was doing. (which is 2ml essential elements and 4ml coral vite daily)
