View Full Version : effects of low calc

01/24/2006, 10:49 PM
First off i wanted to say that your 2 part recipe is amazing and i want to thank you for all the work you do here.
Having said that I have just started to dose your 2 part recipe # 2 because i drip kalk. I started last week after useing kent 2 part calcium buffer, and I'm still trying to nail down the right amount to dose.
For the last 3-4 days my cal has been around the 300-350 level and ive notice some bleaching on some of my SPS corals. Is this directly related to my low cal? my other paramiters are normal.



Randy Holmes-Farley
01/25/2006, 06:28 AM
Thanks, I'm glad you like it. :)

Yes, a calcium level of 300 ppm may well stress corals, and could contribute to bleaching. Especially if the pH or alkalinity are also low.

and I'm still trying to nail down the right amount to dose.

I have a revised recipe coming out in the February reefkeeping (the magnesium part changes if you can find magnesium chloride) and the directions are generally improved).

Here are the dosing instructions from it:

Dosing Instructions

The dosing instructions are basically the same for each recipe, although in any given aquarium one will end up using about twice as much of recipe # 2 as recipe #1 to add the same amount of calcium and alkalinity.

To initiate dosing, first get calcium and alkalinity in roughly the correct ranges. That may require a substantial dose of just the calcium part if calcium is low (below 380 ppm). I would suggest targeting calcium between 380 and 450 ppm, and alkalinity between 2.5 and 4 meq/L (7-11 dKH; 125-200 ppm calcium carbonate equivalents).

This calculator shows how much of what parts to add to boost one or both of the parameters by a certain amount:
Reef chemicals calculator

Then, once things seem roughly set, select a starting dose for routine dosing. Here are some suggested starting doses, but the exact values do not matter too much. For either recipe, use equal doses of Parts 1 and 2.

Table 1. Suggested doses to start with in using this supplement in different aquaria.
Tank Description........Suggested Starting Doses........Recipe #1 Recipe #2
Fish Only With Live Rock........0.1 mL/gallon................0.2 mL/gallon
New tank, few corals.............0.2 mL/gallon.................0.4 mL/gallon
Low Demand.........................0.3 mL/gallon..................0.6 mL/gallon
Mixed Tank.............................0.5 mL/gallon.................1 mL/gallon
Heavy Demand (SPS corals)....1 mL/gallon................2 mL/gallon

After a few days of dosing, note whether alkalinity is declining below where you want it, increasing above where you want it, or stable where you want it to be. Only bother to test alkalinity during this period. It is much more sensitive to over or under dosing than is calcium. Adjust the dose up or down as necessary to increase or decrease the alkalinity.
Once you get a dose set, keep at that dose until there is a substantial reason to adjust it (like it not meeting demand for alkalinity as corals get bigger). When you adjust dose, raise or lower both parts together.

Resist the temptation to keep jiggering calcium and alkalinity independently. They will need occasional corrections, but that should not be the normal course of dosing unless there are substantial outside influences, such as water changes with a salt mix that does not match the tank or an error in making the mixes somehow.

Check alkalinity fairly frequently to make sure the dosing continues at a suitable rate. Maybe check it once a week to once a month (or less as you get more experienced with the system and the tank). Check calcium to make sure it continues on track once a month to once every few months.

Remember to add an appropriate amount of Part 3 each time you finish adding a gallon of Parts 1 and 2.