Backyard Aquaponics
A place to discuss aquaponics

HI TB

Unfortunately I cannot answer some of your questions.

I know there is general consensus that the volume of water in the fish tank should be turned over each hour. Based on this I would be pumping 400gal out of the fish tank each hour.

That would mean, in your system, that each grow bed would be taking 50gal per hour.

In my system (the one I am planning for the future) I was going to base everything on turning over the fish tank each hour, and if I needed more solids filtration then add some more media grow beds.

The time that the water is in the media beds is important as well, because the bacteria need time to convert the ammonia to nitrites, and then onto nitrates. Although this is more of a continual process, the most important thing is to have sufficient filtration/solids removal so that your fish are happy.

As far as the flow rate into, or out of, the DWC beds it would be based on turning over the fish tank each hour.

To have the sump pump into the DWC beds, which flow into the fish tank, causing it to overflow into the media beds you would again need to be pumping around 400gal per hour.

All of this is purely theoretical for me, I have only just put together a very small system and am still working things out.

Thanks, exellant points to consider, so if I pump 400 gal. per hr. and all 4 beds require 250 gal. to fill (63gal. each) lets see,,,xpx. 6.666 gal. per minute I get almost 38 minutes to fill the beds. That might be good and if the DWC required less flow I could adjust water at pump in sump to push excess water flow to F.T. another good point you make is the water in the bed longer gives the bacteria more time to break down the fish waste,,,,hmmm... so the lower in the bed you go the longer the water is there...and say after 6 months can also have worms in there ...hmmm...the syphon empties quickly ...maybe I could insert an inch ana half pvc into the media to carry large waste a bit lower....say apx. midway down with lots of 1/4 inch holes in it 5 or 6 feet long I'm all for better waste digestion... how about a tiny blender or garbage disposal inside the pipe to really break it down. 38 minutes may just work...I've also read that a bit longer time with beds empty encourages bigger root development, how this might effect plant growth i dont know. We may be splitting hairs here. Thanks for the help, great to hear your thoughts....TB

Something else to consider, TB, is that the water required to fill a media grow bed would only account for approximately 40% of the total volume of that bed (the rest of it is filled with gravel/hydroton).

Also, you would probably have your siphon set up to remove water from the bottom of the bed, and be feeding in at the top of the bed, so your water should be getting replaced in the bed each time it siphons out. This is important because any stagnant water will become and anaerobic zone and (to the best of my limited knowledge) create anaerobic bacteria.

hey mate..... just a thought. if your not going to be using this system for eating fish, i have 4 medium goldfish in my aquarium here that i have been looking at 'rehoming' there were initially 10 which were intended for oscar lunch while i was away for 2 weeks, however 4 survived and are now too big for food..... free to good home if your interested?

Thanks for the offer, RB, but the girls are looking forward to picking theirs out already. They are even coming up with different names for what they might look like

I know they shouldn't name them, but we aren't going to be eating them

There was a little confusion about that, so to achieve a 1 to 1 only the 40% of bed volume should be considered and I would assume the DWC beds to count in total volume, but the sump woul also account for some as it would require a bit to start things up. thats 4 media beds 21 sq. ft. each thats 252 gallons is 40% so the sump is going to have to be another big 300 gallon tank and if I add more beds latter I will need another big sump hmmm...gettin crowded allready thanks TB

wITH 2 more DWC beds 21 sq. ft. each adding another 315 gallons to the 252 .. is 567gallons of GB water. I"d need a 600 gal. FT MAYBE I COULD GET AWAY WITH LESS TB

I guess one of the most important things to consider when sizing your sump is to be big enough to hold all the water from the grow beds if they siphon all at once, but small enough so that the pump doesn't run dry if all the grow beds are full (ie about to siphon).

This can be alleviated somewhat by running the grow beds in constant flood so that the grow beds are always full - then you can just top the sump up.

I have not done much in the way of grow bed to fish tank ratios, so I won't be much help there.

I added two gold fish today, though. Spot and Speckles

Very exciting news - I have added another grow bed

Plus I have planted some lettuce and rockmelon in it

Plus I have two fish - Spot and Speckles

I got some smaller size Mary River gravel this time.

Some photos (gravel washing pics tonight, grow bed planted out tomorrow);

If that is 20mm gravel why do you want to go smaller. You are planning a bigger system after this experiment and you just transfer the existing gravel to the new system.

Given that I am currently using clam shells @ 20cm deep I wanted to make sure I had the maximum surface area, hence using some smaller media this time.

Also, I want to see what the difference is for working with, washing, growing in etc.

When I do my larger system I imagine I will use different layers of media (although still not sure what I will eventually use but it will possibly be topped off with hydroton).

As promised last night, here are some updated pics of the new grow bed.

I have planted rockmelon (or cantaloupe for those 'other' states). Actually, I am not sure where it is called cantaloupe, I have lived in VIC, NSW, and QLD..

I have also planted some Butterhead Lettuce.

My fish are still alive 24 hours later too

I haven't been able to get any shots of them yet, but as they learn to trust me they might come closer to the surface.

We call it rockmelon in WA

I too will layer differant media in GB I understand lava rock is very good, slightly porus , good for bacteria. Lava can be paramagnetic, some more than the other,,,can really stimulate growth....a local organic gardener here is writing a book on paramagnetism..Malcolm Beck he may have finished it by now.....I plan to put lava in root zone, hydroten on top....heard the heavier stuff eventually sinks lower its cantalope in Texas...never heard rockmellon, glad to know TB

That lava rock looks to be good stuff! I don't know if I can get some where I am - any other Sunshine Coasters give me a lead?

With the ridiculously hot temps lately I got some better shade going for my young plants and the FT, plus I got a shot of one of the goldies! I am not sure if it is Spot or Speck, and you have to strain to make him out;


I will order some Koi pellets online today.

Here are a couple of shots with the new shade cloth arrangement (of course, since I installed the shade cloth it has been cooler, and overcast );




Oh, I also transplanted my Bhut Jalokia from the first grow bed (the one closest to the tank) to grow bed #2 (the one with the new plants, but without the basil and oregano that are going crazy). The Bhut seems to like his new home