can U tell me the effect of LR weight in a tank?

[tygerfifteen]

I mean for example I have a 70 gallon tank.
So 10 lbs per gallon, 700 lbs of water
with 120 lbs of LR (currently in the tank),and 50lbs LS so doesn't that displace some of the water in the tank? so i would have 530 lbs of water making it a 53 gallon tank???????
so I guess I would have to cut everything to sie when choosing inches per gallon with livestock?
and what about heating? the watts per gallon rule does that change?
Also the watts per gallon (which I don't follow) for light?
please some one help thankx

 

[clarkiiboi]

Sure, definately the LR and LS will take away from the "actual" amount of water in the tank. I can't tell ya anymore---but, now you got me wondering about livestock and such. Just when I thought I had things under control--a loop hole jumps in.
Anyone else got an opinion?

 

[wolffam]

Also don't forget to take into consideration the amount of water in the sump or refug, or both. These can also be used in the formula when calculating. My LFS has a setup consisting of 20 - 10 gal tanks tied to a 100 gal sump running about 3/4 full (75 gals) He calculates his system as being 275 gals. HTH

 

[jarvis]

I really think that the fish stocking limits, watts per gallon of heaters, and watts per gallon of light is just a standard rule of thumb. There is alot of exeptions for the standard rule of thumb. Rules are made to be broken or streched a little bit. I wouldn't strech the stocking limits to much if they are large aggessive fish. I sure wouldnt set up a 10 gallon reef with 80 watts of light and say its a better lighting set up than my 150 with 640 watts of light. Just think practical.

 

[krishj39]

If 1 lb of rock took up as much space as 1 lb of water, then the rock would float around the tank. Rocks weigh more than water by volume, so they don't displace as much as you are thinking, as already mentioned by draxx. Also, with heaters, you shouldn't subtract rocks from your watts per gallon rule of thumb. The rocks have to be heated too! Lighting, doesn't make a difference how much LR you have, the rule of thumb of X watts per gallon should really be more of a measure of how much area and depth the lights have to illuminate, not just how much water they have to illuminate. Livestock, eh, probably should consider modifying your gallons/fish if you have lots of LR, but again, doesn't really matter.

 

[sammystingray]

Anything ADDED into the water.....bioload (livestock), medicine, heat, additives, etc. is effected by the rocks displacing water....example.......medicines, buffers, additives, whatever......says add one drop per gallon.....you have to go by your closest guess as to ACTUAL gallons of water after rocks and such are added.....but lighting does not get effected at all. Lighting still has to travel the same distance through the water to reach the bottom. A DSB does somewhat effect the lighting rule because the tanks bottom may now be 4-6 inches or so closer to the lights......it's all common sense really.....rules of thumb usually suck....use your mind, and forget looking for working rules of thumb in this hobby. As stated......rocks effect a fishes stress level, but I kind of disagree with the way it was stated.....more rocks almost ALWAYS reduce stress. Fish usually feel much safer when they have a nice place to hide when nervous, and not when four fish are trying to hide behind one rock. Too many people want to skimp on the reef lighting......do it right, and the exact water volume won't even matter........