I don’t dose I know nothing about dosing I’m trying to learn more about alkalinity and magnesium and calcium consumption to see if my weekly water changes are good or if dosing will be required I have no clue how to dose I’m quite new and don’t want to completely nuke my reef tank with over dosing something
That's a better approach than allot of what I see on here.
So, the question of if water changes being enough all depends on how many and how much water you change. Is it feasible to do 2 x 10g water changes a week? If it is, you may never need to dose, and water changes will take care of pretty much everything.
Are we talking a 5g water change once a week? Then you'll still be ok for quite some time, but you will need to dose at some point (assuming you get more coral and they start growing).
As far as dosing is concerned, in general people will track alkalinity consumption every day for about a week. They'll take the average consumption from each day and use that as a starting dose. Testing alk around the same time is a good idea, but don't sweat it if you have to test at 7:30 instead of 8:30 or you have to wait an extra hour after normal testing time.
Example
Day 1 - 7.7dkh
Day 2 - 7.6 dkh
Day 3 - 7.5dkh
Day 4 - 7.3dkh
Day 5 - 7.2dkh
In this example, you can see the alkalinity is dropping by about .1 dkh per day. There is a day where it dropped .2 dkh but I would say that would be well within the margin of error for testing. So this person would start with dosing alkalinity to raise dkh by .1 each day. There are plenty of calculators out there to tell you how much of a given product to dose.
Calcium - in general calcium is dosed in a 1:1 ratio with alkalinity. So if you're dosing 10ml of an alkalinity product, you'll dose 10ml for the corresponding calcium product.
Couple thoughts on testing in general.
1. Don't chase a specific number. Pick a range that you are comfortable with and if you test the tank and it's in that range you don't need to do anything. For me if my alkalinity is between 8.5 and 9.5 I do nothing and move on with my day. Same thing with calcium and mag, pick an acceptable range for them.
2. Don't test too often. What I mean is, once you know how much alk you're using you can test less frequently. If water changes are taking care of everything, test the day before you do a water change to make sure it's actually needed. If you start dosing, test everyday the first week to make sure you didn't mess something up, then move to testing every other day, then maybe test only twice a week once it's dialed in.
3. Read the product descriptions and know what the margin of error on your test kit is. The Hanna tester that everyone loves for alkalinity has a margin of error of +/-.3dkh, so that 8.5dkh is actually somewhere between 8.2-8.8 (see why picking am acceptable range is important)
4. When dosing, error on the dosing less. You can always add more if you dosed too little, but it is much harder to bring levels down once the product is in
