Backyard Aquaponics
A place to discuss aquaponics

This is the cold-hardened barramundi that survived while all of his peers perished. The poor little bugger had to put up with just a few litres of water for several days until I installed a heater in my aquarium, but he is happier now that he's warm

I had a 'light bulb moment' the other day and decided to install a valve between inflow and syphon-outflow pipes. My thinking was that I could get some assistance from the water being pumped into the tank when trying to 'kickstart' the outflow syphon which feeds unfiltered FT water to a bank of three (soon to be six) GBs.

I opted to install it at the highest point, ie where the pipes go over the wall. With a twist of the valve handle and well-timed temporary capping of the inflow pipe to force redirection of the inflow across and down the syphon pipe (in both directions to dispel air) and then a twist of the valve to close it again, the syphon pipe continues to suck fish-water! Hooray!

It has typically been a real chore, and a frustratingly tricky one at that, to get the syphon working again whenever the flow has been disrupted. This modification will save me a total of several hours of mucking around each season on a job that often necessitated the assistance of a second person (and they're a scarce commodity at my place). I probably ought to have thought of doing this years ago but, nevertheless, I am presently very pleased with myself.


I just noticed the fish hook that I left on the wall next to the syphon pipe. I found a couple of hooks in the tank, when I was inside it giving it a scrub; silent testimony of the trout that got away!

Yep, that's brilliant PLJ.

After five years of 'going against the flow', so to speak, I have reversed the swirl direction in my tank from anti-clockwise to clockwise. This happens to align my tank swirl with the Coriolis Effect, which causes cyclones to rotate clockwise in the Southern Hemisphere.

I expect to notice a significant difference - NOT!

Ha, we're on opposite sides of the exact same page.

That's really impressive!

That valve is a brilliant idea!

Thanks Boss, Mel and Dom.

You spin me right round baby, right round....

I quite like a mystery but I'm not so keen when it involves the death of my fish.

Yesterday I found a total of five floaters, all with curious signs of physical trauma. The one with the apparently gnawed tail area was found first and I half suspected the sole yabby that inhabits the tank before dismissing the notion.

When the others bobbed up later in the day, all looking like they'd been caught in a net or a pipe, I determined to get to the bottom of the issue. These weren't the first floaters with such injuries this season, either!

I wondered if my network of drain pipes had somehow separated and allowed access to inquisitive fish. I wondered if a bird had managed to clutch them through the bird netting. I wondered about the habits of the three mid-size silver perch cruising around in the depths of the tank.

Finally I remembered that the wrap of shade-cloth, which has for years covered the end of a section of submerged 90mm storm-water pipe (and can be seen in a pic labelled Clean Tank that I uploaded to this thread on 29 May this year), was found floating in the tank the day after I refilled it last month. I wasn't overly concerned at the time, since I use that tank outlet for filling rather than draining the tank, therefore there was no risk to the fish. WRONG!

I strongly suspect that trout don't have the ability to swim backwards. My guess is that these hapless young trout have swum into the open, vertical pipe and, not being able to reverse out, they have swum to the 50mm elbow in the pipe and proceeded to bash themselves to death before finally floating out the revers of the way they came in.

By probing into the dark water for the subject pipe, locating it and then joining another section to it - this one with a cap - the trout death-trap has been sealed to prevent further entry.

Hopefully, I've now stemmed the flow of dead bodies; well at least until the next 'mystery' presents itself!

Over December and January I transferred a few surviving barramundi (Lates calcarifer) from my way too-cool (for barra) big tank to a large, shallow, concrete tank that was better able to be warmed directly by the sun (128 sq m surface area, 15-20cm depth). Apart from discovering a few very large and feral goldfish, I didn't see many signs of fish life in there again until 10 days or so ago. Instead of peering from the side as I usually did, this time I actually walked along the wall to see if I could spy a barra warming himself in the winter sun. Lo and behold I saw one and managed to net him! (That's him, the vertical dark stripe near the wall in the centre of the photo.)

I reckon surviving through to winter in an outdoor pond in this part of the world is an outstanding survival achievement for a fish that is renowned for its preference for very warm water. The barra is now in my aquarium with the sole surviving barra from my big tank. They share it with three goldfish and three silver perch (Bidyanus bidyanus).

That's wild about the pipe. Glad you figured it out. It's always a pleasure seeing your system and tanks.

Thanks, Boss. No deaths for two days so all is good, for now at least.

Good morning PLJ.
I'm dealing with a SLO that is not working properly. You recently drained your tank correct? How well did your SLO perform? I seem to recall you saying the floor of the big tank was pretty clean. Could you give me a little more information about how you get flow through that large network of pipe on the bottom? Is is gravity flow? Pumped? That sort of thing. Is there another source of flow in the Big Tank? Perhaps something like what Gunagulla has?
I'm going to drain our little 10,000 liter tank and I want to try something different to stop the piling up of crap in the wedge shape bottom. I appreciate you advice.

Boss, I draw fish-water from my tank in two ways, as follows:
1. Water is syphoned out over the wall from a depth of between 400 and 700mm. This water is distributed to 4 (soon to be 6) GBs and drains into my below ground sump, where it is pumped back over the 2m high tank wall.
2. Water flows out of the tank under 2m head pressure through one of the 2 original tank outlets. This outlet, however, has a pvc pipe shoved into it, and connected to this pipe is my previously described array of 40mm and 25mm pipes, all with drilled holes in them. This causes solids-rich fish-water to be drawn from all across the 42 sq m floor of the tank rather than just in the immediate vicinity of the outlet. After exiting the tank this water goes in two directions - some is diverted to my radial flow filter (RFF) + biofilter + sump set-up comprising 3 blue 205L drums, and the rest goes through the other RFF prior to being distributed to the 3 original GBs and then draining back into the same underground sump.
Technically, I don't employ a SLO since the syphon at 1. above is drawing solids-free water from a mid level of the tank rather than solids from the bottom.
Although it costs me in terms of lost flow when pumping filtered water back over the 2m high wall, having this depth of water affords me quite a lot of pushing and sucking power due to the head pressure.
I hope this description clarifies how my system works in contrast to your own system.