Need a math wiz to help with dosing

[izzyish]

I recently used BRS's calculator to help me dose Alk and CA. Maybe, I'm entering my water volume wrong because I can get it right. Please help...

I have a 120 with about 120 lbs. of sand, 100 lbs. of rock, and a 36 gallon sump that is filled about 2/3's of the way up, which is probably about 20 gallons considering the skimmer, pump, and misc. equipment subtracts water volume.

I want my calcium at 420, it was at 380. Using 100 Gallons of water, BRS's calculator suggested I dose 358 mL. So I started to dose 100 ml's at a time.

First dose of 100 mL rose my CA from 380 to 400. Second dose of 100 mL rose my CA from 400 to 420. Testing was done between 2 days. It only took 200 mL's to get it to the level I wanted it at, not 358 mL's.

My question, considering it took 200 mL's to raise my CA from 380 to 420. What would my true water volume be?

 

[OnceTrueFalseBr]

so you have approx 150 gallons of water total?

let me try some math

1 ppm

if one pound of X inside of 120,000 gallon = One part per million

thats 1 lb of X inside of 999,600 lbs Water = 1 ppm
16 oz of X inside of 15,993,600 oz Water = 1ppm

Convert Gallons of Water into Pounds
w = 8.33 q (1)
where
w = weight of water (lbs)
q = volume of water (US gallons)
Example - Converting Gallons of Water to Pounds

150 gallons can be converted to pounds as
w = 8.33 (150 gallons)
= 1249.5 lbs (round up to 1250 for simplicity)

150 gallons = 1,250 lbs
thats 20,000 oz

so 15,993,600oz / 20,000 oz = 799

16oz / 799 = 0.020

so your part per million is:
0.02 oz into 20,000 oz = 1 ppm

0.02 oz = 0.59147059375 ml

your ml ppm = 0.6

I hope i'm right LOL none the less that was fun haha

ppm desired increase x 0.6ml = ppm
(40)ppm desired increase x 0.6ml = 24 ml

im still testing equations LOL well my brain just decided to stop working and thats all i got LOL

i am sure im totally wrong somewhere lol

 

[izzyish]

so you have approx 150 gallons of water total?

let me try some math

With the rock and sand displacement, also inculding all of my equipment, I would assume about 100 gallons total. However, per BRS's calculator, if I enter my total water volume at 55 gallons, and put in that I want my CA to go from 380 to 420 it tells me that I should dose 200 mL's. Which is what I dosed to get my CA up to 420. Does this mean I only have 55 gallons of water? Seems a little low to me.

 

[OnceTrueFalseBr]

what is your tank dimensions?
http://www.firsttankguide.net/calculator.php

48 x 24 x 24 = 120 gallons?

how deep is your sand bed?
if it is 4 inches you lose 20 gallons right there volumetricly speaking of course. every 2 inches you lose 10 gallons

the 100 lbs of LR is the same thing. you might lose another 20 - 30 gallons from that. add in the equipment overflow box, water level, yea you lose quite a bit...

you just might be clearing 80 gallons total water volume...

 

[izzyish]

what is your tank dimensions?

how deep is your sand bed?

I'm still going through your calculations there...:hmm5:

60*18*26 and my sandbed is 2 inches.

Thanks for the in depth look, I appreciate it!

 

[OnceTrueFalseBr]

With the rock and sand displacement, also inculding all of my equipment, I would assume about 100 gallons total. However, per BRS's calculator, if I enter my total water volume at 55 gallons, and put in that I want my CA to go from 380 to 420 it tells me that I should dose 200 mL's. Which is what I dosed to get my CA up to 420. Does this mean I only have 55 gallons of water? Seems a little low to me.

also remember your test kit might be a little off too...

 

[OnceTrueFalseBr]

I'm still going through your calculations there...:hmm5:

60*18*26 and my sandbed is 2 inches.

Thanks for the in depth look, I appreciate it!

no problem, I am learning from this thought processes too!

damn them nano 20g reefs are barely sitting with 5 gallons of water LOL

 

[BeanMachine]

Sorry may have missed it but are you using BRS supplements?

 

[OnceTrueFalseBr]

sorry may have missed it but are you using brs supplements?

+1

 

[izzyish]

Yes I am, I'm dosing 2-part.

 

[izzyish]

A little bit off topic but I've heard of people dosing 2-part and I've also heard of people using lime water in their ATO. Is this something you can do together or should you only be doing one?

 

[m0nkie]

A little bit off topic but I've heard of people dosing 2-part and I've also heard of people using lime water in their ATO. Is this something you can do together or should you only be doing one?

you can use either one or both together. my LFS use lime water, but certain tanks need more calcium, so they supplement 2 part.

 

[disc1]

You can't really calculate your water volume like this. There is too much noise in a calcium kit. 380 might have really been 390 and 420 might really be 410. There is a significant amount of error.

Well, to be fair, you can do what you want but you have to put a big error range on it. So you might have something like 150 gallons plus or minus 100 gallons. That doesnt really help you much though.

 

[oceanlassiter]

Each cubic foot will hold 7.5 gal of water.