The Puffer Forum

For most of my set-ups I do actual working measured volumes at first filling, write that down and keep it. Some set-ups have little substrate or rorkwork, others have so much of both that I have to add sump(s) for needed volume. Phones are not me - I am moderate/severely visually handicapped and most phones are useless without better vision than I have. Most of you would be horrified if you watched me reading on-line or with my CCTV enlarger/color changer. As many books as possible I listen to rather than reading.

RTR wrote:Especially if you add the prominent warning that tank nominal sizes have no relationship to reality - other than that the reality is always smaller, sometimes a lot smaller.

Huge +1 to this, too many people think an x size tank holds x amount of water, it actually holds about t lol. I know what I mean

Quite a few folks use approximately 70% of nominal volume as a possible working volume. I do have some tanks that fit into that approximation, but when you have a FOWLR set-up, I am unlikely to have even a 50% of nominal volume display. Heavy rock-work such as Rift lake tanks can have the same effect. That is part of why all of my tanks are set with measured initial working volumes. I am willing to do extra work up-front to avoid issues later.

the 70% I use as a guide for FW tanks. SW is a totally different beast and needs to be measured accordingly. A perfect example would be deep sand beds vs shallow, then -30% or more for live rock. So yes the actual holding volume of water what the label states and the actual living space is reduced greatly.

It is amazing how many folks never think about what their tanks' working volumes really are.

Agreed, approximations are a good guideline but nothing comes close to knowing exactly what your tank holds once decor etc is in.