2 part dosing, tank volume question.

[Frozn]

Ok.. This is more so directed towards Randy but I know there are others with great info that know a thing or two. So..

I just started dosing the two-part and I've got my mag closing in on 1300 which started at 1180 before the dosing. My Alk is resting at 6dKH and my calc at 380.

I have a 90g display with a 35g refugium which is approx 3/4th full perhaps 5/8ths. I've been dosing based on a total volume of 80g after displacement, should i be dosing as such or should i do approx 115g dosage.

I'm only trying to raise calc and alk atm as the magnesium is going up quite steadly and with ease.

Dosage:
40ml calc
65ml alk

I was wondering others opinions as to the amount I should dose to get my lvls up approx 8-9ish dKH with a calc of 420

[coraljunky]

Try this and click on the volume calculator.
http://home.comcast.net/~jdieck1/chemcalc.html

[Randy Holmes-Farley]

Only trial and error will give you an accurate dosing scheme. I'd stick to equal parts dosing unless the calcium actually gets too high. If calcium is too low, give it a one time correction to fix it.

I give my dosing recommendations here:

An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System
http://reefkeeping.com/issues/2006-02/rhf/index.php

from it:

http://reefkeeping.com/issues/2006-02/rhf/index.php#15

Dosing Instructions
The dosing instructions are basically the same for each recipe, although any given aquarium 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 adjust calcium and alkalinity to roughly their correct ranges. This may require a substantial dose of just the calcium part if calcium is low (e.g., 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 in order to boost one or both of the parameters by a certain amount:
Reef chemicals calculator
http://home.comcast.net/~jdieck1/chem_calc3.html

Then, once things seem roughly correct, select a starting daily dose for routine dosing. Here are some suggested starting doses, but the exact values do not matter much. The suggested doses apply to both recipes.

After a few days of dosing, note whether alkalinity is low, high or on target. Only bother to test alkalinity, not calcium, during this period, because it is much more sensitive than calcium to over- or underdosing. Adjust the dose up or down as necessary to increase or decrease the alkalinity.

Once you have determined the proper dose, continue it until there is a substantial reason to adjust it (such as falling alkalinity as the corals increase in size). When adjusting the dose, raise or lower both of the recipe's 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's parameters or an error in making the mixes.

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

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

[Frozn]

Ok, so I should still dose equal parts of calc and alk even though my alk is on the low end..

So I should then just start dosing higher amount to bring them up to where they are and then find a daily amount that keeps them even.. Ok think I just need more time to get in the niche of things hehe..

Thanks a bunch!

[Randy Holmes-Farley]

Yes, equal parts. If you boost alkalinity from 6 to to 9 dKH, your calcium will still be just below NSW levels.

Each 2.8 dKH boost to alkalinity is accompanied by about a 20 ppm boost to calcium.