Backyard Aquaponics
A place to discuss aquaponics

I would pump at least the volume of your fish tank into the fish tank each hour. If your pump can't provide enough flow to the fish tank and to the other parts of your system, it means you probably need an additional pump just for the fish tank or a bigger pump to handle the flow and head requirements of the system and towers.

Thanks TC...I'll try and check that 3.3 gpm rate. Really not wanting to get another pump just for the FT.

Tricks to getting the most flow from your pump,
1-upsize the pipe out of the pump up to the highest point.
Pumping straight up in larger pipe will provide the least amount of friction resistance. If you are using only the minimum size pipe (say you are using irrigation pipe with barb fittings that is nominally 1/2" and your pump has a 1/2" outlet, then those barb fittings are restricting the flow and your pump is having to work harder and probably not providing you with as much flow as it could.) So if you go to a larger size PVC (who's fittings don't restrict flow nearly as much) pumping straight up and then you can branch and reduce from there, you may find you can get more flow out of your pump.

If you don't believe me, I have a plumbing demonstration I do where the class times as I fill a container using a pump hooked up with the 1/2" irrigation tubing, then they time it again as I fill the same container again with the same pump but using 1/2" PVC. The container fills considerably faster with the pvc and If I upsize to 1" pvc I can get even more flow. (You still never get more flow than the pump is rated for, it will always be less since you are pumping UP AND through pipes which add to resistance.) The higher you have to pump up, the less flow you get.

Thanks TC...I'm familiar with flow charts and resistance...having working in irrigation for 30 years. But, thanks for reminding me. I'm going to try and upsize main line to 1.5" and see if that helps. The pump is a 45 GPM, and with that, my 1" is restricting the flow a bit. I'm used to working with hundreds of feet of pipe, but resistance is resistance.lol Also, maybe drain sweeps vs. 90 elbows...maybe get a bit more.

Coachchris,
Also make sure the pump isn't being restricted on the intake, If it is a pump that has the option of using a sponge or not, pull the sponge off since it quickly gets slimmed up and can definitely restrict flow through the pump. I would only personally use the sponge filter if you have fry in the tank. Just make sure you have a grate that can keep sticks and leaves out of the pump and check/clean it regularly. A 45 gpm pump is a fairly large pump in the realm of Backyard Aquaponics if it is indeed performing up to spec. I think the biggest I ever used was rated at about 60 gpm at 5 foot head and that was certainly overkill for all but the largest systems.

Important thing about sizing pumps is you want to move at least the volume of your fish tank through your fish tank while also doing whatever else you need to do but you also want to make sure your pump does it efficiently. A cheap pump is usually not a good idea if it means you will be using 10 times the electricity. I learned that lesson quickly after getting the electric bill since my first big system pump had been a "free" above ground swimming pool pump. Upon getting the first electric bill, I rushed out and spent $500 on an energy efficient pump that would save me $600 a year compared to the free pump.

What kind of specs would one look for to know how efficient (energy-wise) a pump is?

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Well first of all you look for a pump supplier that can show you a pump curve or chart that tells how much water the pump will supply at different heights. So this will tell you what size pump you need to supply some given amount of water at a particular height.

Then you compare the wattage and/or amperage the pump uses with other pumps that can supply the amount of water needed at the height needed.

Often for small pumps you can find a listing of how many Watts are used.
For larger pumps you may find it listed as amps or kilowatts.
Keeping in mind that wattage or amperage ratings may only be an estimate since the amount of pressure can affect how much power is actually used and also when the motor starts up there will be a peak amperage that happens and then things settle down to a lower level for running.

The Aquatic Eco Systems catalog often lists or has links to pump curves as well as the wattage or amperage ratings for their equipment. When ordering pumps from other hydroponics sites or from the web in general it can sometimes be quite hard to find out some of this information. If you send an inquiry to a seller and they can't supply you with a curve or chart for flow at different heights and can't tell you what the wattage or amperage rating for the pump is, then I would not buy that pump from them unless you can find the information elsewhere and be absolutely certain the pump they are selling is the same pump that you got the information for.

In some cases it can sometimes be more efficient to use separate pumps for different purposes. For example maybe you have a pump that uses 300 watts and can do everything for your system. But what if you found that by separating the plumbing feeding your towers you could feed them with a 50 watt pump and then use a separate 145 watt pump to feed the fish tank/grow beds and have more than enough flow, then you would only be using about 200 watts for the system and perhaps you would only run the tower pump during the day so save even more electricity.

Keeping in mind for electricity the math is West Virginia (WVA)
W=V x A
Watts = Volts times Amps
So if you know your voltage at your house and the amperage of the pump then you can multiply to get the watts used.

So if the voltage at your house is like 124 volts (I've noticed that the power seems to run a bit hot or higher than 110 or 120 most places I've been) and you know your pump uses 0.7 amps so 124v x 0.7a=86.8 watts. Now I bet it is likely that some pump manufacturers might actually list a pump as using only 70 watts but if you plug it through a killowatt meter and check it, you might find it actually using more because it is possible that they used different numbers when figuring out how much wattage the pump would use. For instance if the manufacturer is in a place where the power is a different voltage perhaps they assumed the power was 110 Volts which would give an answer of 77 watts and then the part of the company doing the packaging decided to round the number down to make it look better for marketing purposes..........Well you get the picture.

Then you multiply the wattage by the number of hours the pump will be used to find out how many watt hours or kilowatt hours your pump will draw to figure out how much electricity the pump will need per month and then multiply that times your electric service rates to find out how much it costs you to run your pumping per month.

Ingenious. I've done each of those calculations in other contexts but had never considered comparing efficiency... effectively calculating watts/gallon/unit time. Thank you!

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I am just in the exploring/planning stages. We are planning a greenhouse of about 16x16 feet (4.8x4.8 meters) since the winters here in Missouri (USA) can be cold, although not usually as cold as we have had this year.

Tentatively, we are planning on a flood and drain system.

I have a couple of questions.

1) In the first post in the thread the ration of GB volume to FT volume could be 2:1.

I assume that this is related to the amount of fish based ammonia->nitrate for a fish concentration of average density to support that much growing area. (If that is a false assumption, please let me know). I can't see how that can work. Even if you assume that 55% of the GB volume is in grow media and 45% is liquid, it seems to me that with one GB you would deplete that FT by almost half and with 2 GB the poor fish would be in only 10% of the tank volume. I would prefer not to have a sump if I could avoid it. I would also prefer not to have to run the pump constantly (would I have to do that if I had either a CHIFT PIST or constant flood system?) Could/should I just keep the same number of fish that I would have needed but increase the water volume?

2) I saw someplace a table comparing fish species with temperature ranges for tolerance as well as the optimal temperatures and did not copy the table at the time. I have been unable to locate that table again. It seemed that tilapia might be the best for Missouri. The summers are hot and the aquaponics will be in a greenhouse (although the greenhouse will be well ventilated in the summer and probably the tank can be shaded) so I don't think the fish tank temperature will rise too high in the summer. In the winter the heat gain from the greenhouse as well as, if needed, supplemental heating should be adequate. But, I am unsure of what to consider. Would koi be marketable as they grew in size if we wanted to look toward some degree of income production rather than focusing on fish harvesting for our table?

If you want timed flood and drain, you should consider having a sump, as that allows the water level in the fishtank to remain relatively constant. That would be CHIFT PIST. As for ratios, you want to be sure to stock to what your biofilter can handle, you can scale up your fishtank as much as you want.

I would be redescent to stock tilapia in Missouri. There are more appropriate fish for your climate. What do you catch when you go fishing?

Thank you for the quick response.

I think that I am becoming less opposed to CHIFT-PIST and can see the benefit of a sump. It is good to know that balancing fish numbers rather than concentration of fish to the biofilter capacity works.

If I want to turn over the fish tank water each hour would that be the combined volume of the FT and sump tank or just the FT?

The usual fish around here are bass, largemouth and small mouth, bream (bluegill, red ear, etc) and catfish. I am not a big fan of cooked catfish, but I see some posts on the forum that suggest that tank raised catfish do not have the "muddy" taste I do not enjoy. All of these fish seem to survive well in the lakes and rivers in the area. The botanical garden in St. Louis has a large Koi population in the lake in the Japanese Garden section and grass carp also do well.

I would like to be able to utilize the fish as more than a source of nitrates for the garden section, so I think that grass carp (which is not usually considered an edible fish around here - although I hear that they are considered fine elsewhere) may not be our first choice. What do you see as reasonable options for species choice?

I look forward to learning more as I move past planning and into building.

I was wondering if I needed to obtain fish and place them in an aquarium to start developing some healthy bacteria and give some boost to the FT water when we get ready for that part. Any thoughts?

Thanks again

JL

So sushimi then?



Just the FT. You mentioned that you didn't want the pump running all the time. Can I ask why? A pump running all the time turning the FT water over 1/hr should use significantly less electricity than one that turns itself on and off during the hour yet still turns the water over on average 1/hr.

If you do go for a fish that will require heating be aware that it is much harder (read expensive) than you think. To give you an idea imagine how much wood, gas or electricity it would take to keep your greenhouse close to the water temp you want.

I second the opinion that you DO NOT WANT tilapia in that cold a climate. I'm in central FL and it gets too cold here to keep tilapia without supplemental heat.

And I can assure you that Aquaponically raised channel catfish taste the same as Aquaponically raised tilapia. The only difference is texture when you over cook them, tilapia gets stringy while catfish gets dense and perhaps a little tough when over cooked.

If you have an objection to catfish because they are not kosher, then I would recommend raising Bream, however they will be far smaller (6 oz is perfectly respectable harvest size for bluegill) so you usually have to harvest a mess of them to make a big meal.

I've raised all three, Tilapia, Bluegill and Catfish. I still grow Bluegill and Catfish but Catfish is our primary fish. Here in FL with our hot temperatures much of the year the catfish can grow from fingerling to 3-5 lb in 12 months time. The tilapia I've raised (mixed gender blues) I was lucky to get them much bigger than the bluegill most of the time and they are hard to fillet and because water temperatures falling below 55 F meant time to panic to keep them from dieing if it dropped lower was a real pain and to have tilapia actually eating and growing you really need the water temp above 70 F. With bluegill and Catfish they can survive water down to nearly freezing and they keeping eating (though a bit less) down to about 55 F and they seem to survive heat just as well as the tilapia do provided you have supplemental aeration when it gets hot.

Even with a cold tolerant warm water fish like catfish or bluegill or bass, you are likely to need to add supplemental heating to your greenhouse during the colder months to keep water and pipes from freezing unless you are planning to basically shut the system down (just leave aeration going for the fish to keep their tanks from freezing over) when you are getting really cold weather. Unless you go with really high tech greenhouse design and an insulation blanket over it that you close overnight and open during the day, you can't depend on a greenhouse gaining enough warmth during the day and keeping it overnight to avoid all freeze dangers in your climate without active supplemental heating (active supplemental heating needs to be part of the initial greenhouse design, it doesn't work well as an afterthought.) I would guess that in your climate that most unheated "hoop house" type greenhouses are seen more for season extension and not as a way to do year round Hot house growing (that would be keeping the temperatures from ever falling below about 55 F so that you could keep hot weather crops, tropical and tilapia alive.) Even in central FL one would need supplemental heating to guarantee NOT killing tropical plants/fish in a hoop house during a cold week with hard freeze nights. I KNOW your climate has colder weather than that Normally.

I would recommend at least 300 gallons of individual fish tank volume to grow catfish though. If your tank is smaller than that, go with Bream.

I usually stock 1 catfish per 10 gallons of fish tank and I like to have at least 20 gallons worth of grow bed to keep up filtration for each catfish. It is ok to have twice as much fish tank volume as you need but you have to make sure you don't stock more fish if you don't have more filtration to go with it.

I have stocked as much as 1 bluegill per 3 gallons of fish tank before provided I had 6 gallons of grow bed to filter for them. I don't recommend this for your fist season with a system though!!!

I have always turned over more than the volume of my fish tank each hour, I consider that a bare minimum. I tend to move closer to twice the volume of my fish tank each hour even with added supplemental aeration. If you are going to only pump for 15 minutes each hour, definitely add supplemental aeration.

Keep in mind that doing timed pumping and still trying to turn over your fish tank volume each hour means that you probably need to move the total volume of your fish tank in 15 minutes (in other words you need a pump 4 times bigger than you would have for constant pumping.) Search for pumps that you can find pump curves or charts that tell you how much the pump will move at whatever height above the water the pump has to lift the water to (don't run plumbing overhead, it will cost you too much in electricity to get a pump big enough to do that.) Don't buy a cheap pump, spend a bit more money on a pump that is energy efficient and at least a tiny bit bigger than you think you need.

Check out the thread good pumps bad pumps for pump advice.

Also came up in this thread recently

viewtopic.php?f=8&t=20540&start=15

I say use the search thread but it doesn't seem to be working at the moment.

Fortunately the good pump/bad pump thread is stickied (for a reason)

viewtopic.php?f=8&t=1409

You guys are being so helpful and I am truly appreciative.

I had not considered that a continuous flow pump could be smaller than a flood and drain pump, but that is, of course, correct. In addition, my assumption was that intermittent pumping had to be more energy efficient than continuous, but, again, I stand corrected.

It sounds like catfish may well be the fish of choice. Again, my thanks for all the information.

We are planning a hoop shaped greenhouse, but are going to use 16 foot cattle panels instead of PVC tubing. We are planning a double layered polycarbonate covering.

For heat, we haven't decided, but are considering a wood stove and fan.

I need to research about purchasing catfish. If I stock based on adult size than it seems like it will take a long time to get any useful quantity of ammonia->nitrates from small fish. Should I try to get larger fish or stock more than I need and then thin them out as they gain weight?

So much to consider... Fortunately, we still have snow on the ground and are not ready to build the greenhouse. But i am a data junkie and like to know as much as I can as I start a project.


Edited for a typographical error and to insert a missing word.