How to figure actual water after LR and LS?

Curlsoc

Premium Member
So, I've been trying to figure out appx how much water is in my tank after the live rock and sand. I have 4 1/2 - 5 inches of LS, and probably 150 lbs of LR, some of the LR is under sand as the base. The tank is a 110. Any guesses or ideas on how to figure this out. I'm trying to figure this out for future fish stocking. Or, is there a better way to figure out the fish thing? I'm so used to the freshwater rule of thumb.....
 

snusa

In Memoriam
It's really hard as you have to calculate the volume of your rock dimension that displaces in the water. I did not say you can't.
 

Curlsoc

Premium Member
<a href=showthread.php?s=&postid=10415320#post10415320 target=_blank>Originally posted</a> by dattack
Well the answer is how much water did you mix up to fill the tank?

Ahh, therein lies the issue. Rock was added in different stages, and we did a reaquascape this weekend, adding more, so not entirely sure. I'm suspecting that I now have around 80 gal, but that's such a guess.
 

d34532

New member
You would have to measure how much water is displaces by the rock and sand. You would need to containor that has small units of measurement (oversize measuring cup if you will) and place the LS and rock into it one at a time and measure how much it displace.

Example:
2 gal "measure cup" half full (1 gal of water)
1lb of LR
1lb of LS

If you place 1lb of LR and it moves the water line up to 1.2gal then it replace 0.2gal

if you place 1lb of LS into the water line at it goes to 1.1gal then it displace 0.1gal

IE 10lb LR = 2gal of water 10lb of LS = 1 gal of water. Just made up number but you should get the idea. LS and LR would have to be an avg weight as some are heavier or lighter.
 

Bergovoy

Moved On
actually the weight and volume displaced would be not equal. Sorry, each rock would have different density and different mass, so each rock would need to be measured, and depending on how accurately you measured it would trickle back to the accuracy of the water volume

I dont think it that necessary to accurately determine the water to teh nth degree...

I would try to figure out by guesstimate about how much water is displaced by the rock, if you have a lot of rock then you have less water, so guess, or just figure the size of your tank, less 10-15%

I would imagine the smaller the tank the more critical it would be, and since I have a big tank, I have never had to think that way..

So, good luck

bill
 

d34532

New member
<a href=showthread.php?s=&postid=10415873#post10415873 target=_blank>Originally posted</a> by Bergovoy
actually the weight and volume displaced would be not equal. Sorry, each rock would have different density and different mass, so each rock would need to be measured, and depending on how accurately you measured it would trickle back to the accuracy of the water volume

I dont think it that necessary to accurately determine the water to teh nth degree...

I would try to figure out by guesstimate about how much water is displaced by the rock, if you have a lot of rock then you have less water, so guess, or just figure the size of your tank, less 10-15%

I would imagine the smaller the tank the more critical it would be, and since I have a big tank, I have never had to think that way..

So, good luck

bill

Nice try and like I said already the numbers were madeup so it will be easier to understand. I also stated some rocks and sand will be lighter or heavier. I also said the smaller the units the better.

If you would like more and exacting numbers then here is the recent rock weight to water displacement.

75lb (really 78.8lb rounded it to a easier number for easier math) of LR displaced ABOUT 3gal of SW. which in my case 1lb avg displaced 0.04 gal of water. In my case it took 25lb of LR to displace 1 gal of water. If you want more exacting number of what 3 gal divided by 78.8lb its about 0.038071065989847715736040609137056 gal per lb avg.

IE
So my 10lb avg of LR = 0.4gal of water displaced

If you want a more exacting number I have a digital scale and I can look for the smallest unit containor so we can really get the exact displacement.

DISCLAIMER: Those numbers are my number your rocks and sand maybe heavier or lighter. I might have done a typo in retyping the numbers feel free to check my numbers.
 

Curlsoc

Premium Member
Goodness, open a can of worms, why don't I? If I use Lam's calc, I displace about 8 gal, and Bill's guess, about 16 gal. I'm guessing I'm more to Bill's end.
 

d34532

New member
Curlsoc,

LoL Its all in good fun but it depends the type of rock you have mine might be more density or mass.

You can't really look and guess the water displacement because it would look like I had a 10-13gal displacement in my 30gal tank. Very little water for fish to swim. I recently(yesterday) got my 78.8 lb of LR and remove 5gal up had to put back about 2 gal back. Remember our LR is not solid so water does go into the rock and we can see all these holes and the volume of water is in the rock pores, holes, etc.
 

Curlsoc

Premium Member
Makes sense, Lam. But, if I was figuring for swimming space, then the visual guess might be more correct, since I can't count the little pores and holes in that. But, as for water changes, then the more accurate calculation would be better.

I think I'm going to go redo my goldfish tank today, easier to think about :)
 

Bergovoy

Moved On
can of worms? And here I am , deap smack right in the middle of it again...

No matter what, it will be a guestimate, for like LAM said, each rock will be different density, god cant even make them consistant.

So, guess, hopefully it wont be that critical, (you have a slightly larger tank), and the fish arent that sensitive, or needy.

btw: is there a sump involved in these calculations, and is there water in the pipes??

good luck

btw: girl or boy?
 

d34532

New member
Susan,

for water change wise I like to just take the total volume and to 10% weekly change, which is really more then 10% WC but which ever is best for you.

Lam is a guys name.

The Pic is of Ayumi Hamasaski the top Japanese "pop" singer.
 

d34532

New member
Bill,

I was at the last SCMAS sitting next to Steve G. I was also messing with you since I heard you like to be in the middle of a can of worms. I agree large tank doesn't matter too much and there are a lot of factors like pipe, sump, pumps, etc.
 

Curlsoc

Premium Member
Yep, there's sump, pipes, etc of course. For water changes, I have been just doing 15 or 20 gallons, 20 right now until the tank is done cycling and I get the nitrates down and then probably to 15 for maintance. I figure there's around 30 in the sump, plus 110, so 15 gal is about right for 10% for the future.

Bill: Girl. Oh, and Tyson is installing a better pump this weekend for the tank than the Rio 17, we got an external Pan World 100. Better?
 

GTR

Active member
When I started ZEO I really wanted to get an "accurate estimate" of water volume. So I took various size pices of rock and placed them in a bucket of SW with 1/2 g gradutation marks in it. The water displaced gave me an idea of what each piece might be.

So with a basic idea of each size I was able to take a visual inventory of all the rocks in the system. When all what said and done what I had then was another wild guess. :lol:

SteveU
 

anthias_lover

New member
75lb (really 78.8lb rounded it to a easier number for easier math) of LR displaced ABOUT 3gal of SW.
I think 75lbs of LR displayed way more than 3g of SW. If you take all 75lbs of LR out of the tank, I'm sure you add/replace way more than 3g of SW.
 
Top