How are my numbers?

[Glen McDonald]

Hello everybody, I am trying to size my system. I have 300 square feet of media bed. It is going to take me about 175 gallons to flood my beds. So in order to not stress my fish I will need an 800 gallon tank. I am going to have a swirl tank, a degassing tank. and a reservoir. I am thinking 100 fish to start.

Do my numbers make sense? Please give me your feed back.

[TCLynx]

How deep are you media beds?

300 square feet but only needing 175 gallons to flood doesn't work if your beds are 12 inches deep.

If you have a media bed system with 300 cubic feet of grow beds that is like 2220 gallons of grow bed and you would want to figure in water level fluctuations of about 1110 gallons (it would actually be less but I usually just figure half the grow bed volume to give my self some leeway.)

But you say you are going to have a reservoir, do you mean a sump tank?  If you will have a sump tank then you do not need to plan the fish tank size to deal with water level fluctuations since that is what the sump tank takes care of.  So going under the impression you have 300 cubic feet of grow bed, I would then say you need a sump tank between 1200 and 1500 gallon capacity.  Your fish tank, well I would probably go for a 1000 gallon fish tank just because 800 gallons isn't a size I'm used to seeing and you will normally not fill a fish tank up to the rim or the fish tend to jump out.  I'm  guessing that my 1000 gallon fish tank is filled to about 900 gallons.

So, why would you bother with a swirl tank if you have 300 cubic feet of media beds?  It seems just an added expense and something you then have to clean out every few days or it becomes a stinking mess.

If you are doing flood and drain media beds you probably don't need to bother with a degassing tank either but that is up to you.

Cycle up fishless and a system with that much media bed will be up to handling quite a lot of fish.  But What kind of fish?  Some types of fish, 100 of them might be the perfect number while other types of fish.......... it will also depend on what your goals are for the system.

If your media beds are not 12 inches deep, then a whole different set of numbers will need to be used.  So what does 300 square feet of media bed really mean?

[Chris Carr]

It costs time and slightly more expense, but starting with something smaller and experimenting/proving your system is balanced for your growing circumstances, then scaling the system by doubling/quadrupling/etc it in size later may be a safer way to mitigate disaster on a larger scale. The smaller added expensive in the beginning is insurance that you wont make a much more costly mistakes later.