understanding the economics

[Lance Rose]

I am trying to keep books on my setup so that I can gauge how to expand without robbing a bank.

I hope to kickoff a discussion about relative cost and economies of scale. 

For my current setup, I have "free-sourced" just about everything but the fish and plants. But now I am running into some stuff I did not account for, which will cost me a little. For example, the testing kits.

I have water in 2 55 gallon barrels. So I guess I have about 100 gallons of water. I have 50 coppernose bluegills. The growbed is 1 55 gallon blue barrel split in half.

My startup cost were about $50. $25 for plants and $25 for fish. I also had a little plumbing couplings to buy.

If I had paid retail for all the stuff,

Barrels (?) I am seeing $30 each on a couple of websites = ($90).

Frame wood ($30)

PVC (10' 1", 10' 3/4") plus couplings, glue ($30)

Rocks (this one is hard) If you buy bags at Loews/HD (15 X $3 = ~$45), Or $1 per bucket at a local aggregate seller (~$15). 

Pump, ($45 at Loews/HD)

Around $200. Sound right?

So startup will cost between $0 (catch the fish from pond and get plants from other source) to $250

In a 3'X2' grow bed, I think I can get some strawberries, Okra and a couple of tomatoes. I might get $20 worth of produce.  If I manage to kill 0 fish, I will get 50 good sized bluegills which have a value of (what?) If I buy fish at walmart, it is $4-$5 for a package of 2. So for eazy math, I will say $2 per fish = $100.

So my output value is in a range of $0 (all die) to $150 if everything goes right.

My ongoing cost are food, electricity, water and testing.

Food so far is a bag of commercial feed, I got that for $15. I expect to use a lot more in the future, but right now, not so much. 

Electricity is ?. I have no way of measuring the actual usage. I'm not sure how to convert watts or amps to actual unit of energy I get charged for.

Water. I have a well, so my water use is basically electricity. Plus I am adding a little water every other day. This will be more in the summer. But again, I dont know how much this cost me.

Testing (~$15/kit). I am testing once week for 1 week so far. I'm not sure how long this kit last. I'm guessing 2 months.

So if a bag of food and a test kit cost me ~$20/month.

Am I missing anything? I am trying to make an Excel spreadsheet to cover my cost as I go.

[TCLynx]

With only 100 gallons of fish tank and only 50 gallons of grow bed, YOU HAVE WAY TOO MANY FISH!!!!!!!  Especially for a new system.

If the system was not cycled up fishless, you should be testing more like once a day for the first couple months.  Your test kit (if it is an API freshwater master test kit) it will probably last a couple months testing most days.  You don't have to test nitrate every day but the pH, ammonia and nitrite should be tested more often through initial cycle up and after the system is more mature you should still test pH more than once per week since if it crashes it can happen in less than a week and you need to recover immediately to keep from crashing the system.

[Chris Carr]

I would have to agree. 5x the output of fish from plants from the system does not make sense. For a system this size I would not stress yourself too hard trying to crunch numbers on justifying the cost. You should approach it as an investment into it whatever you are comfortable putting into a hobby and collect all your output as gravy to reduce your food bill. MAYBE you will have some money in your bank account you weren't expecting to buy some extra lumber or PVC at the end of the month to expand it.

[Lance Rose]

Thanks. That is the kinda thing that is hard to find on the internet. I will start testing daily. 

So to be sure I understand, I have 50 small fishes( 2"-3"). I plan to cull as they grow. (I use the word plan loosely...). 

How many should I have? I was thinking the idea was 1 lb of fish per cu ft of grow bed. I have about 9 cu ft, but I dont have 8 lbs of fish. I have a cattle pond I can unload fish into.

I appreciate the info.

TCLynx said:

With only 100 gallons of fish tank and only 50 gallons of grow bed, YOU HAVE WAY TOO MANY FISH!!!!!!!  Especially for a new system.

If the system was not cycled up fishless, you should be testing more like once a day for the first couple months.  Your test kit (if it is an API freshwater master test kit) it will probably last a couple months testing most days.  You don't have to test nitrate every day but the pH, ammonia and nitrite should be tested more often through initial cycle up and after the system is more mature you should still test pH more than once per week since if it crashes it can happen in less than a week and you need to recover immediately to keep from crashing the system.

[Lance Rose]

I'm not looking to use the numbers to "turn a profit". I would love to, but I doubt it. I just want to get an idea of what stuff cost. I am thinking about a much larger, but still not big, system next year. I hope that I can use some of the data to plan better. This is all off-the-cuff this time. I would also like to get similar info from people who have bigger systems. Lastly, I hope to be a source for the next person. 

Thanks.

Chris said:

I would have to agree. 5x the output of fish from plants from the system does not make sense. For a system this size I would not stress yourself too hard trying to crunch numbers on justifying the cost. You should approach it as an investment into it whatever you are comfortable putting into a hobby and collect all your output as gravy to reduce your food bill. MAYBE you will have some money in your bank account you weren't expecting to buy some extra lumber or PVC at the end of the month to expand it.

[Lance Rose]

On a different note, I have secured another blue barrel. So I need to plan a way to get this integrated into my system. That will be my weekend! That will balance my growbed and fish tank. But it might take a few days/a week.

[TCLynx]

If you cycled up the system Fishless and the bio-filter were already robust and ready to go, I would put say 12 Bluegill into a system with only 50 gallons of grow bed total.  If you haven't cycled up the bio-filter yet and just added fish, I would say start with 6.

Yes I know they are not 1 lb yet!!!!!!  But just because a cubic foot of gravel can support 1 lb of fish does not mean you need to have that many pounds of fish in the system.  THAT is the UPPER limit of the amount of fish you should stock, NOT then necessary amount!  It doesn't take very much fish to grow lots of plants.

Get most of those fish out of there or you will probably loose them all when the ammonia spikes beyond belief.  What do your water tests say now?

[Chris Carr]

Sorry I didn't mean to say you shouldn't budget or estimate costs at all. I misinterpreted what you said as you planned to reinvest profit to expand the system and of course you should but I don't think planning on it will work out as well as hoped. I don't think I have ever done any DIY experiment that came in on budget, even a pessimistic one planning for rebuilding and gas for a billion trips to the hardware store :)

Regarding your electricity usage, your bill should say how much a kwh is (killawatt x hour). That is how much it costs to run 1000watts for 1 hour. If you know the wattage of your pump(s)/lights you should be able to estimate costs based on how long they are on per day.

If you don't know the wattage of a pump, I believe by law it has to have input voltage and amp usage on it. wattage = volts x amps

Lance Rose said:

I'm not looking to use the numbers to "turn a profit". 

[TCLynx]

You can also get a kill-o-watt meter that you can plug a pump into and it will tell you how many watts a device is using (since sometimes the labels are not very accurate) and your actual electrical usage will vary depending on the actual voltage delivered to your home.

[Chris Carr]

Yeah a meter would make more sense for accurate measurements where 10% inaccuracies can make a difference but buying a meter to measure the difference between $10 and $11 a month is likely not worth the investment.

[TCLynx]

Right Chris, if you are only worried about measuring this one little thing, the meter would not be worth it.  They are of more interest to people who need to go around getting rid of the electricity vampires in their house to improve overall energy efficiency while they figure out how big a solar array and battery bank they would need to go off grid.  Seeing as that kind of scale suddenly a few watts here and there adds up to thousands of dollars in capacity difference in sizing the whole thing.

[Chris Carr]

Yes for sure. I agree. I forget how I came across it the other day but here were 2 interesting devices for just that purpose (energy vampire squashing)

http://www.amazon.com/Belkin-Conserve-Socket-F7C009q-Energy-Saving/...

http://www.amazon.com/Belkin-F7C016q-Conserve-Power-Switch/dp/B005M...

[Lance Rose]

OK. I am going to pull about 40 of the blue gills out. That will leave me with about 10. I did not get a chance to do a test today. I will in the morning. Thanks.

I really appreciate the input. In my current setup, the meter would be a bit of overkill. If I plan to scale up next year, it will be good to be ready. How I proceed next year will depend on how I get through the Texas summer. I am researching water cooling systems, I would like to do a heat pump were I run the water from my tank to the sump. 

Since this is a hobby, I am having fun working with it. But a bigger system next year may get past "Hobby" size.