Backyard Aquaponics
A place to discuss aquaponics

Just spent a couple of hours trying to rebalance the flows after topping up the sump. Went out this arvo and saw some wilted seedlings in the GB and the siphon was sucking and not breaking. My system needs to be more robust - at the moment it is a very fine line between enough water through the towers and too much in the FT and through the GBs. A change in level in the ST can affect the head enough to change flows and stop the siphon from working properly. I need another GB and another SLO to deal with the extra flow needed to turnover the FT once an hour

I'm hearing you.

I have exactly the same issue!

With your pipe, you could use pellets soaked in water until they soften, then squeezed, and they will sink.

With fish already that large, you wont need to wait long until they are plate sized!

They are 6 or 7mm sinking skrettings pellets - the greedy buggers hit them at the surface and none make it past hence the pipe idea .
I am starting to look at the larger trout with a degree of speculation.

So glad i found your thread!!! you have given me many ideas!! how is that bird netting holding up? and where did you get it?
love the paint job on your towers.

Thanks Arkieeskimo. Most folks around here with fruit trees have to use bird netting to save some fruit from the parrots. Local hardware and garden stores stock it in prepackaged lengths or rolls.
The parrots cut holes in it, so you have to replace it regularly . I asked around for people to bring our their dead netting as each tower took around 3 metres. Its doing a great job in the towers distributing the water and supporting the plants. There's a closeup photo of the biofilm on page 7.

Note to self - excellent science based fact sheets and calculator on AP by Dr Wilson Lennard (thanks Gunagulla ) http://www.aquaponic.com.au/fact%20sheets.htm

I have discovered how to make it rain for 2 days and confirmed it by repetition - I just need to top up my ST, and it starts raining that night and doesn't stop for 2 days! Its happened the last two times, so it must be true . At least I don't have 300mm of rain to contend with like folks around Sydney - we just have the tail end of the system here in Gippsland with light rain/drizzle.

pH two days ago was down to 6.4, and was 6.0 today , but this is a good thing because it means my system is aerobic and nitrifying. Sprinkled 3/4 cup of dolomite in the GBs for the rain to wash in to slowly raise pH, will check again this arvo. Still running with a trace of ammonia and nitrite, possibly because the feeding has crept up from ~50g to 60g per day and my system is running a bit close to the edge with 25 growing trout, 400 litre GB volume plus the unknown capacity of the 20 towers .

My towers have a combined volume of 127 litres filled with bird netting that is well covered in biofilm and has good water distribution. This has a much greater surface area than 20mm gravel, but have no idea by how much. If it has 4 times the surface area, then I would have just on enough biofiltration (for nitrification of ammonia) for my current stocking rate according to Dr Lennard's calculator, but not enough to deal with solids which go directly to the GBs. I could remove solids &/or add some extra GBs . With the improved flow through the FT, there are solids visibly building up at the inflow to the CF 1/2 barrel GB, but at least the bottom and corners of the FT are now clean. I am thinking of trying a RFF in a clear spring water bottle like in Titus' system viewtopic.php?f=1&t=21619&start=30 , but am not sure how much flow it could handle and some replumbing would be required . Someone recently posted a link to a paper comparing swirl and radial flow filters which I must read http://integrated-aqua.com/wordpress/wp ... epaper.pdf

Nitrates are off the scale at 160 ppm, but hopefully the tower plantings will kick off and use it up. Although, this cooler, cloudy weather has slowed growth. I need to build the extra GBs quickly or look at off loading a few trout. Will back off the feeding to 50g/day for the next few days. Its been too wet to try getting pellets down a pipe to the smaller fish down near the bottom.

Here's another photo of my garden - I really didn't like the grey concrete block garage wall, so this is what I did to it

Joc the rain will cause your pH to drop, just watch that your pH reading of 6.0 is not off your colour chart and actually lower than 6.0

Nice art on the garage wall, JoC!

Hey Joblow, yes I am watching that. The dolomite sprinkled in the GB seems to have raised it and held it at 6.4 for the past few days. I will get some builders lime and potassium bicarbonate to alternate pH adjustments so that I don't get my calcium/magnesium balance out of whack with too much dolomite.
Thanks JimV

My son did a good job of looking after the AP system and all the other creatures for the past 3 days while I was off to Adelaide for a meeting of the clan for a combined "Man from Snowy River' ANZAC day birthday party for my brother and dad (2000 km round trip). The driza-bone oilskin coats came in handy with the weather, and the multiple camp oven stews and damper were rib-stickingly delicious.

The system lost a bit of water while I was away with stray tower leaks, so topped it up today. It has been getting cold here, and the trout didn't smash the food today - gosh, some even reached the bottom of the FT! Must revisit the trout feed calculator to check on feed rates with the current temperature.

Don't worry about trying to stick to the calculator- the amount they eat varies from day to day, sometimes with no obvious cause. Mine ate 175g today, but 2 days ago only wanted ~70g, and the water temp was only around 13.5C max today, 2 deg cooler than the 25th.
Feeding small amounts more frequently, rather than large amounts once or twice a day means less waste in my experience.

Time for an update...
My 25 rainbow trout are feeding well and growing nicely. The largest are pushing 28cm with most at least 25cm. Still have a couple that are only just over 20cm, but they are filling out more now that some of the pellets are reaching the bottom. I like to watch them as they feed to make sure they eat up all the pellets and check on their behaviour and condition.

With all this good food, there are plenty of nutients, rather too much nitrate at over 200ppm, but ammonia and nitrites are behaving, bouncing around between 0 and 0.25ppm.

Good nitrification means my pH is constantly dropping. Shellgrit helped initially, then I used dolomite, but half a cup every few days is probably getting the calcium:magnesium ratio out of whack and adding too much sediment. Gungulla alternates builders lime and potassium bicarbonate (or hydroxide). Didn't want to buy and store a 20kg bag of builders lime and I haven't found a local source of potassium bicarbonate yet. Thought I would try a solution of wood ashes. Its strong stuff and worked really well without adding any solids, so I have gradually increased pH from 6 to 6.8 over a few days. According to Wikapedia, 'much wood ash contains calcium carbonate as its major component, representing 25 or even 45 percent. Less than 10 percent is potash, and less than 1 percent phosphate; there are trace elements of iron, manganese, zinc, copper and some heavy metals.' I also use woodash slurry to cure olives which removes the bitterness and adds a subtle smoky flavour.

Plant growth is slow with the cooler weather, but still getting a couple of salads a week.

Still have one of the 20 towers to fill and plant. 10 towers of strawberries are all alive with some varieties appearing to do better than others - will be interesting to see how they all go over a full season. Still occasionally develop random wicking leaks out the corners of the planting holes which can lose a lot of water if not noticed and fixed by rearranging the bird netting.

Collecting spoons from op shops to make a 'culteryfish' sculpture to hang over the metal art gates (which are yet to be made ).

And last but by no means least, a big thankyou to the experienced APers for advice on nutrients, feed rates and pH on various threads

Builders lime is really cheap- and 1 bag is a lifetime supply! just store it in a plastic garbage bin with a decent lid and it should be fine. Otherwise, do you know any builders? or even just drop into a building site and ask for half a kilo. I use it and Potassium hydroxide, not bicarbonate due to the detergents in Ecofungicide, but I do use that for foliar spray against powdery mildew, which sort of works.

Feeding small amounts more frequently, rather than large amounts once or twice a day means less waste in my experience.

+1 and its a lighter load on your bio filtration.

Was out and about shopping today - will end up getting a bag of builders lime. Dropped into the hydroponics shop to see if I could get some KOH, they had a 'pH up' no-name made up solution that contained KOH, but a phonecall to the dude who made it could not confirm if there was anything else added. Gordon, where do you source your KOH and in what form?

Scored a big bag of spoons from an op shop for a couple of $$ so should have enough scales for the 'culteryfish' now.

Best of all, we got a metal cut off saw, so the gate frames and new GBs will happen a lot quicker now that I have a new toy to play with - its all Colum's fault, his GB clip convinced me to move beyond the anglegrinder

Dasboot, I make sure they eat all their pellets as I watch them each time I feed. Although the novelty of this will probably wear off a bit and life will get in the way, so a couple of smaller feeds is probably safer when that happens. I have checked the WQ a couple of hours after feeding just to make sure I'm not getting short term spikes and it was all good (where is the emoticon for relief?).

Thanks for your input