smeagol108 Posted June 22, 2015 Share Posted June 22, 2015 So I'm looking for a formula for how much things like alk, cal, and mag will be affected by water changes. For example I have a six gallon tank with five gallons water total volume. Alk in tank is 7.2 Alk in new mixed saltwater is 11.7 I change 1 gallon which is 20 percent. So adding one gallon of new water with alk of 11.7 will raise the 7.2 to X? Who's still up to date on their high school math? Help me out folks, it's been a while. Link to comment
ReefWeeds Posted June 22, 2015 Share Posted June 22, 2015 OMG. yeah, I tried that a few times and apparently it has been way too long since algebra for me. But i"m following in the event someone comes up with a good formula! Link to comment
tibbsy07 Posted June 22, 2015 Share Posted June 22, 2015 I'm going to wait to see if I did mine correctly, lol. I always have to double check my math. I'll see if I was correct when someone else posts. I got an Alk of 8.1 when I did it. Link to comment
smeagol108 Posted June 22, 2015 Author Share Posted June 22, 2015 I used to be so damn good at math too. Was my favorite subject. Now I'm an IT guy for ten years the only math I really need is logic true/false. And some basic math for subnetting but theres cheats for that too. My roommates a math teacher so I should just ask him, but he left for Spain yesterday for the summer. Lucky teachers. Lol. I am trying to use this formula to keep things more stable in my nano, as well as decide on maybe a salt change too and whether to change any of my infrequent manual dosing. In other words, just trying to keep alk more stable as my sps have been thriving but I know they can do better. Cmon high school nano reefers where are you at??? Link to comment
ReefWeeds Posted June 22, 2015 Share Posted June 22, 2015 HA! These two posts cracked me up. My math now completely consists of return on investment analysis. And I probably rely WAY too much on excel formulas. Link to comment
HarryPotter Posted June 22, 2015 Share Posted June 22, 2015 I used to be so damn good at math too. Was my favorite subject. Now I'm an IT guy for ten years the only math I really need is logic true/false. And some basic math for subnetting but theres cheats for that too. My roommates a math teacher so I should just ask him, but he left for Spain yesterday for the summer. Lucky teachers. Lol. I am trying to use this formula to keep things more stable in my nano, as well as decide on maybe a salt change too and whether to change any of my infrequent manual dosing. In other words, just trying to keep alk more stable as my sps have been thriving but I know they can do better. Cmon high school nano reefers where are you at??? Haha y'all really cant do concentration changes? Let me get out my textbook for the formula Link to comment
tibbsy07 Posted June 22, 2015 Share Posted June 22, 2015 Haha y'all really cant do concentration changes? Let me get out my textbook for the formula I did it how we do it in lab, but i like to double check. Link to comment
smeagol108 Posted June 22, 2015 Author Share Posted June 22, 2015 I didn't remember what it was called otherwise I would have googled it. Trust me I tried. Link to comment
tibbsy07 Posted June 22, 2015 Share Posted June 22, 2015 I used a modification of concentration1 * volume1 = concentration2 * volume2 That is how we calculate how much of something to add to another to get a specific concentration at a specific volume. basically i just multiplied each concentration by its volume, added those, then divided by 5 the total volume and got the new concentration. Link to comment
Mojado Posted July 21, 2015 Share Posted July 21, 2015 Post water change ppm = tank water ppm * (1-water_change_%) + new water ppm (water_change_%) Edit: so for your example 7.2*(1 - 0.2) + 11.7*(0.2) = 8.1 Link to comment
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