Backyard Aquaponics
A place to discuss aquaponics

There is some lengthy discussion going on in one of the spider valve threads about something sort of like this.

+1 on going with a larger pump. I have a 10 gallon aquarium system that uses a 258 gph pump, I've done as much as 50 gallons with such a small pump, and my 300 gallon quarantine system is currently running continuous flood with a 700 gph pump. All my systems have air stones running full time. (Though air stones bubbling in and of themselves might not be super efficient at aeration, they do increase the circulation of the water within the tank which helps aeration as well as helping solids move through the system.)

Ok, back to that system design, I highly recommend starting a member system thread to post this question to get specific help for your situation. Pictures and all highly appreciated. Also if you haven't already done so, reading the rest of the useful info section and the basic info section can help you out as will reading a few of the big long member system threads.
Good Luck.

Thanks hydrophilia and fishfodder,

I'll go for a higher rated pump and put more water through through the garden beds?

Question: Can we run too much water through the garden beds?
Could excess water flush out the bacteria from the media??
For example, if I turn over the fish tank volume every hour, that will be 560 litres going to each growth bed. The voids within the bed are only about 220 litres, so 340 litres will run straight through the overflow back to the fish tank. I guess that's OK, the media may have done some cleaning of the water and the water will have wet up the plant roots. Then the last 220 litres will be held in the growth beds until the siphon activates.

I plan to slope the floor of the growth beds down to a single low point so that the last bit of water doesn't cause waterlogging and so that aeration can reach right to the bottom.

Well, Creative1 seems to like running his beds full (with an inch left dry) 24/7, so I would guess not. I like the flood/drain concept and reason that it does have real benefits, but have not actually tested the benefits for plants and oxygenation of water.

Erm.....I doubt it. I think the area that is highest in bacteria is right where the water enters the system and that gets the most flow. Once again, untested. *grin*


If you are running some form of autosiphon (like a bell siphon) it will probably (well, it BETTER!) suck faster than the pump fills. I have a 25mm pipe in my bell siphon (reduced to 18mm at the bottom for better start) with about a 20cm drop from low-water to bottom of pipe and it seems to suck about 25 liters per minute. If you got a 1500 l/min pump it would probably run about 1000 to 1200 liters/hr, so use one or two sizes larger for your bell siphon.


I worried about that too, but it is really not necessary: as long as the water fluctuates by most of the growbed (20cm?) everything will be happy.

Hi...
What i meant about the fish tank not being filled all the way to the top, so, in a 120 gallon tank, i'd have 100 gallons of water...

hoping to start the build next weekend, after gassing out water, i figured i'd pick up some feeder goldfish to start everything circulating before buying fingerlings....


___________________________
Vivite Vibrance

Okay, sorry for the revival of the thread - it was very informative!

I need some clarification please:
3kg (fish) for 100 liters of water (grow bed)
AKA
6.6 pounds (fish) for 26.5 gallon of water (grow bed)


1. 3kg of fish is combined weight right and not a reference to 1 huge grown fish?
2. 100 liters of water is the full size of the grow bed or the amount of water a grow bed holds (40% of total volume)?

Thanks!

No....

It's 3kg of fully grown fish to 100lt of growbed MEDIA (I.e Biofiltration)

Yes it is referring to all fish combined, but if you have only one fish, you'll have to eat it when it is 3kg

This is ABSOLUTE max unless you are a seasoned expert.

Do not run this stock ratio in a new system. And work up to it gradually.

Don't put 3kg of small fish in and try and keep the total biomass at 3kg by eating them as you go. This will end in the good old "help! My fish are dying" thread appearing.

Okay, so if I have a 100 liter grow bed and I fill it to the top (not that I would!) with media, I now have 100 liters of media right?






Great advice thanks!!



Well I look forward to the "my fish are dying" thread but only because I am harvesting them... at 3kg LOL

No, it's 100liters of volume of that growbed but the media would completely fill it. if you pour water into it you'll find that even though it's full to the top of media you can still add about 30-40L of water depending on the size of the grains of the media. the smaller the grains of media the closer to 100L of the volume of GB it will get and you won't have enough space even for the water. even so, water will still manage to get through it.

We say that media takes up about 50-70% of the gb volume and the water can take the rest.

So when you calculate how much water will go into your growbed... it'll be about 30-40% of under your gb's dry volume. and if you add up all your growbeds volumes that water occupy, you get your minimum total for the size of the sump tank you need. Unless you sequence it doing one growbed or two at a time.

As for the stocking, well you could always make another system and divide up what fish you got to lessen the stress. I have about 2 aquaponices systems running one is 2 small beds over one fishtank and the other has 3 medium sized beds with a fishtank and sump and I'm about to reinvent my old cubby system again but with major differences to last time and hopefully more permanent. after that if all goes well (as if!) I might be on my way to a major system that I'm going to make my own grow beds and use an already manufactured pond tank and bury it into the ground with maybe a few inches to spare above ground. Because you see, if you have a large pond, you add one growbed at a time and if there isn't enough plants using the nites up, get another GB and if the plants are using up all the nites, get more fish! With lots of consideration in the health and well-being of both plants and fish in every instance of course.

Jeeeaz I can't believe I didn't reread it properly...
I meant it would NOT completely fill it.

Sorry, maybe it's my lack of common sense, overwhelming ignorance or a combination of the two...

I understand how to calculate for the sump. That seems pretty straight forward because when designing for aquariums, the thoughts are similar.

Maybe my question should be in another topic but wondering now about the 3kg/100l ratio. Is the rule of thumb a 100 liter grow bed or 100 liters of media?
As an example, I have a 26 gallon grow bed. If I fill it with media, I still have a 26 gallon grow bed but I can only fit at most 10.4 gallons (40%).

Is the ratio related to how much grow bed media I have (I think so) or how much water I can fit in the GB (don't think so)?

Am I confused or am I relaying the difference correctly?

Thanks in advance for putting up with my silly questions.

wow... I see why you're getting confused. I went back to reread that again and I see where you're coming from. you have a good point. I would say it's the water not the media but DrLuke said Media so something's fishy going on here.
We need someone like Rupe to confirm this. I thought it was water 40% to 3kg of fish but I could be wrong, I can't believe it because I've been running on this idea for the last 3 years!

I was thinking about your last post just now. and when I think about my past conversations with others, I always though of the container volume not the media or the water in it. Because to measure either of those in any given situation would be nearly impossible some places are hot and others cold and we all use lots of different media so using media or water would be toooo variable and container/planter size would be much easier to compare.

I am glad you see my confusion!

Sump Sizing:
So it seems that in sizing the sump, what amount of water that could be dumped into the sump is important. Obvious I think.

Fish Stocking:
When sizing for stocking, I would think it is the amount of media that could support the nitrifying bacteria to help sustain the system (and feed the plants).

I know this post was about ratios for sump planning but a new user (like me) needs to plan for the amount of fish because without fish, how do I feed my plants in AP? lol

Thanks again

you're very welcome

Okay....

I didn't have time to read both your post in detail, but me just reiterate and clarify my post.

I am only talking about how to calculate the stocking density of your system based on filtration capacity, nothing to do with sump or water volume. Water volume is a secondary restriction to stocking dentistry. Filtration volume (effective surface area really) is what is going to dictate your system's ability/power to convert ammonia->nitrites->nitrates and keep your fish alive...not the water volume.

1) the recommended MAX stocking density on this site is approximate 3kg of grown fish per 100 lt of media. It has come about through years of experience and also some technical debates on media surface area.

2) most people just say that if you have 100lt tub filled right to the brim with media, then you have 100lt of media. This seems to work well enough, but obviously u could be conservative and only calculate media as being equal to the tub volume minus the ~40% water in the tub.

3) the IBC of aquaponics actually follows the rules I have outline fairly closely, but does not state it explicitly. They are running approx 250 lt of media, which equals 7.5kg of fish, let's say 7 to be safe. If you are growing them to 500gram, this means 15 fish MAX. Take into a that this is a beginners guide and we are using the "don't run this in a new system" rule, you knock about 30-40% off your stocking rate...if I remember correctly, the IBC of aquaponic recommends somewhere between 8 and 12 fish in a new single IBC system.