When is a gallon a gallon?

[Lori_inFL]

I am planning on a WaterBox Peninsula 6025 and shopping used equipment here and FB etc. So, the tank is 136.6 g and total system is 195.1 g. But the sump at 9" would only be 18 g. So water volume would be more like 155 less sand and rock plus whatever is in the plumbing lines.

I have started keeping a list of necessary equipment and the correct model for a given brand for my size tank. So my question is when the manufacturer gives a tank size in their specs, are they referring to DT (136 in my case) or total system (155 likely or 195.1 rated)?

Unfortunately some equipment breaks at say 150 g and that might be ok or do I need to go up to the next model? I get that say a protein skimmer has the tank load that adds another layer that also implies wiggle room. Return pump suggestion at 4 - 6 times per hour seems like that would be times the 155 g; but I read somewhere that you don't count the gallonage in the filtration. Really confused about UV. Powerhead or gyre seems like only the DT would count.

Thanks for any assist on clearing this up. Not necessarily wanting to be overly anal about the math here; thought the question would be good for the Thread Starter contest!

 

[Üter]

I am planning on a WaterBox Peninsula 6025 and shopping used equipment here and FB etc. So, the tank is 136.6 g and total system is 195.1 g. But the sump at 9" would only be 18 g. So water volume would be more like 155 less sand and rock plus whatever is in the plumbing lines.

I have started keeping a list of necessary equipment and the correct model for a given brand for my size tank. So my question is when the manufacturer gives a tank size in their specs, are they referring to DT (136 in my case) or total system (155 likely or 195.1 rated)?

Unfortunately some equipment breaks at say 150 g and that might be ok or do I need to go up to the next model? I get that say a protein skimmer has the tank load that adds another layer that also implies wiggle room. Return pump suggestion at 4 - 6 times per hour seems like that would be times the 155 g; but I read somewhere that you don't count the gallonage in the filtration. Really confused about UV. Powerhead or gyre seems like only the DT would count.

Thanks for any assist on clearing this up. Not necessarily wanting to be overly anal about the math here; thought the question would be good for the Thread Starter contest!

its how many gallons the tank holds, not the displacement from rock, sand etc...
i.e. 100 gallon tank. add 100 gallons of water. then remove 50%. place your 100 pounds of rick in and 100 pounds of sand in. add back the water you removed and see what's left for you subtraction for a truer amount. All rock has a different poundage and displacement. but it will give you a better idea later when you need to add a certain amount of medics to X gallons of tank water etc...

 

[Lori_inFL]

Thank you. So say I had 20 gallons left over so I have 80 g of water in the tank. Is that the size I want to use for selecting say a protein skimmer?

 

[UncommonSense]

Thank you. So say I had 20 gallons left over so I have 80 g of water in the tank. Is that the size I want to use for selecting say a protein skimmer?

This is a difficult question to answer; just like many manufacturers will inaccurately label their aquarium/sump “volume” as the outside dimensions of the tank/sump. In addition, many manufacturers “capacity” measurements are assuming the interior dimensions of the tank/sump are filled all the way up to the top rim…

So, many manufacturers do everything they legally can to over-claim their system’s true operational fluid capacity.

Same goes for much of the equipment! Often, manufacturer will add the biggest number they reasonably can, volume-wise to their product!

This problem is complicated further in skimmers because there are often multiple “volume ratings”, based off bio-load…

I’m frustrated with this aspect of the hobby particularly now as I’m designing filtration on two separate systems…

The best bet I’ve found is to reference BRS recommended tank size at a given bio-load notes on their skimmers… then, make a note of skimmer body size, minimum neck ID, etc to make some educated guesses about your sizing based on design, and minimum neck diameter; more than claimed tank filtration capacity!

 

[Üter]

Thank you. So say I had 20 gallons left over so I have 80 g of water in the tank. Is that the size I want to use for selecting say a protein skimmer?

protein skimmers are usually a range. like 75-120 gallon etc...

 

[UncommonSense]

I frequently use this, and their other calculators for volume, area, etc… the tried and true method of figuring out how much water you’re actually able to hold (excluding displacement of everything added to the system) is to just figure out how much volume you’ve got! — there’s ~7.48gallons per-ft3

Volume of a Rectangular Prism Calculator

Use this volume of a rectangular prism calculator to quickly find out the volume of your box.

www.omnicalculator.com

 

[IceNein]

If you use a tank calculator, almost universally they give you the "gallons" value of a tank as the total interior volume of all the glass boxes. If you have an AIO it is especially deceptive, because different chambers will be significantly lower than the main tank water level.

I was confused about this a little at first too, but I just gave up caring. It's puffery and they all do it.

 

[Lori_inFL]

I was confused about this a little at first too, but I just gave up caring. It's puffery and they all do it.

It seems like you just need to do the best you can and then let the rest go. Hopefully you don't have to wind up selling used equipment as you need to upsize or downsize the stuff you bought.

 

[UncommonSense]

It seems like you just need to do the best you can and then let the rest go. Hopefully you don't have to wind up selling used equipment as you need to upsize or downsize the stuff you bought.

Regarding skimmers; it seems like the smart move is to go with something slightly oversized, then “detune” it, so to speak… controllable DC pumps make a lot of sense here!