Backyard Aquaponics
A place to discuss aquaponics

I wouldn't change water - its weakening the system when you do that. Just feed lightly, as in a teaspoon a day until it comes down - probably not a mature system yet and the fish will be fine for a week without feed.
Salt if you think you need to - I wouldn't bother if the nitrite goes down after light feeding.

My system had ammonia (.5 to 1) in it all winter as I was feeding heavily but didn't have nitrite, so in your case its probably just an immature system or you haven't got enough bacteria yet.

You did cycle before adding fish so that's good.

Small world indeed. I put a net over the IBC and tuck into the gap between cage frame and IBC - this will stop them jumping into the gaps between IBC and cladding. Food goes through it easily.

Thanks for the advice Jay. Today's water test was the same as yesterday with pH a little lower at 7.0, NH3 steady at 0.5, NO2 steady at 2, and NO3 around 20. I gave them 1 pellet each (a couple of slow ones missed out) and that was it. They are all looking okay. Will continue to monitor.

I now have 19 of my 20 towers filled with old bird netting and 15 of them on line. Will turn on the rest when my bigger pump arrives hopefully this week. The six towers that have been running for a week have a fairly even water distribution and quite a good biofilm on the netting with a bit of algae where the sun shines through the planting holes. Hopefully the others will catch up and help with the NH3 & NO2.

I changed the gal mesh over the fish tank for well tucked in black bird netting as suggested.

The towers look awesome! stunning in the light - almost like totem poles

Thanks Jay

Today's water test
pH falling to 6.8
ammonia rising to 1
nitrites falling to 1
nitrates rising to 40-80





I'm feeling a little less stressed now that nitrites have dropped back to 1 ppm. The fish look great. I gave them ~30 pellets yesterday, and the same today. They hit them hard as they are so hungry and the few slow coaches near the bottom miss out.

It is lovely hearing the trickling and burbling of the AP system and the occasional splash as a trout rises outside the bedroom window - when half asleep it sounds like we are camping on the banks of a mountain stream in the Victorian high country, but in a really comfortable bed with an en suite The effect is enhanced with the faint smell of burning bush wafting in from the control burns in the hills to the north.

Great graph. Yeah you can see that it was cycled but your bacteria is at young stage and wasn't ready for the stress put on it from feeding heavily. I'll show this to my student he will be interested as we are at a stage just before you with nitrites now going down in initial cycling.

Feeling much better about the system now that the nitrite spike is abating.

Water test results
----Yesterday--Today
pH-----6.8--------6.6
NH3---0.25------0.25
NO2----1---------0.25
NO3 ---80--------40

Fed them short rations of 30 pellets yesterday, and upped it slightly to 40 pellets today. Gee they hit them hard!!
Still haven't found my thermometer, but I can vouch that the water is cold as I had to fish around in the sump tank up to my armpit to try to find the water test tube that slipped out of my hand -they go into stealth mode underwater! No luck, will try again when the sun is shining.

@joc - Did you check your power cable before reaching your hand in??

Regards

Hey Curious, the cable is protected following your warning, and I suppose I had already 'tested' to see if the ST was live by dipping my hand in to get the water samples - we do get complacent, don't we! My problem is that the pump is still plugged in through the bedroom window, and it is a big walk around and through the house and back out to switch it on and off. Will be getting a sparky in shortly to put in a couple of outside powerpoints for the AP system and the new hot water service - better get on to that

The test tube has remained in stealth mode, or the yabbies have eaten it or hidden it.

Felt comfortable enough with the readings to go away to visit my folks at Easter. My neigbour, who looks after our dog and cat, now has 5 chickens and 25 fish and possibly 5-7 yabbies to contend with. She brought her mum over to feed the fish (I left out containers labelled for each day to prevent overfeeding). All was well when I returned, although the ST was in need of topping up - still could not find the stealth test tube. Filled the ST to the brim with tank water & added a cap of seasol. Gave the fish 4 handfuls of food given the low NH3 & NO2 results - its doesn't get a chance to sink as they smash it as soon as it hits the surface . Woke up to pouring rain! We have had around 50mm or 2 inches since the early morning, and the ST overflowed as it was so full after topping up yesterday . Bucketed out a bit onto the garden to give a bit of headspace - it is still raining steadily.

Jay, glad you find the graphs useful. I have updated them with the latest figures. My pH is dropping steadily despite the tray of shellgrit in the ST - it is down to 6.4. When do I start buffering with potassium bicarbonate? I got the eco-fungicide at the Melbourne Flower & Garden Show a couple of weeks ago just in case .
How is Yarragon going with cycling & new fish?




The neigbour across the road had a wooden paling fence replaced, and I have gradually carried over all the palings, rails and posts. My O/H has cut up & stacked most of the scrappy palings for firewood and I have been denailing rails and posts. A couple of the rails were to be used to attach the Fish Farm gates to the brick wall, but they have come up so nice that my O/H has commandeered them and the posts to make a garden bench seat, so I have to find something else to attach the gates to...

Hey Joc, 6.6 is ideal in AP.
You can use shell grit in a stocking hanging near flowing water for gradual PH buffer. When you initially put it in there are finer parts that will change PH pretty much straight away.
You can try a teaspoon of lime when you need to raise it - you're system is new and will change rapidly. As it gets older you can add more and it won't change so rapidly - I think this has something to do with Carbonates in the water?

Inspiring, as usual JoC!

Okay, so I had fun feeding the trout yesterday a couple of times - probably around 100g all up and they were still keen for more. This morning the pH has dropped a little more to 6-6.4 and ammonia has risen again to 0.5, with nitrite rising a little to 0.25, and nitrate at 40. Had a heap of rain yesterday ~60-70mm.

I was trying to work out the weight of my yearling trout based on their length, and stumbled across this trout feed calculator https://docs.google.com/spreadsheets/d/ ... edit#gid=0 in this thread viewtopic.php?f=26&t=12411&start=15 which gave me 47 grams/day for 25 fish at ~20cm long at ~19oC, which is half of what I gave them yesterday. I will stick with the calculator for a while as they seem to be growing even on the very short rations of the past week, and the piggies seem like they will eat until they burst so feeding until they stop doesn't seem like the way to go.

Hey Joc, be careful if your pH test kit is indicating pH 6, as the pH can drop well below that and you can't tell with the usual test kit, which could make things difficult for the bacterial colonies in your GBs. When feeding the trout over 100g of pellets per day, I've found that the many kilograms of shell grit I have in my 1st system is not enough to buffer against the falling pH, so I use Calcium hydroxide = Ca(OH)2 = builders lime, and Potassium hydroxide = KOH. These are both strong alkalis, so you need to be careful using them, and they provide no buffering effect, but with careful use are great for controlling a rapidly falling pH. I alternate their use, so providing a balance of Calcium and Potassium for the plants.

Potassium bicarbonate, KHCO3, makes up 94% of the ingredients of Eco-fungicide, the other 6% is wetting agent/detergent, so I think it is best reserved for use as a foliar spray, although others have added it to their system water, apparently without any problems due to the detergent. I guess it depends on what quantity you use- but Eco-fungicide is a very expensive way to control pH in comparison with other methods.

I'd recommend getting a reasonable quality pH meter too, they are much better than the low resolution reagent testing.

Thanks Gordon, is there any problem with using a bit of dolomite garden lime which I have handy as it would have other goodies for the plants? To be safe, what sort of increments should I add for my system which is ~1700 litres total?

With regards to the test kit, I think I am about to drop off the bottom edge of the chart. Today's reading was still visibly above 6.0, but only by a little and at the rate it is falling, I will run into unknown territory over the next few days. Given that I have topped up with tank water and had so much rain yesterday, I think the water will be poorly buffered so will change rapidly with either bacterial activity or any additives.

Dolomite is good and will work as a buffer too, it will add Magnesium as well as Calcium to the system. I've never used Dolomite in my system, so not sure how readily it dissolves, but sprinkling a few cups of it into the GBs, and washing it in so it mixes with the system water would be a reasonable start. It is a buffer like shell grit, so wont have any drastic effect on pH, but you do need to make sure you take enough action before you are unable to get a reading due to it being off the scale.
Builders lime is inexpensive, and a bag is a lifetime supply for a backyard AP system, ATM I'm throwing 15 or 20g into the ST once or twice a week, and a bit more than that of KOH, and my pH is in the low 6s, with ~7000l of water, and ~220 small trout and 30ish 20-30cm Murray Cod. Feeding has been around 100g of ox heart and 90ish grams of pellets per day.

For your 1700 litres, I'd try 5g of Ca(OH)2, dissolved in water and make sure it is well diluted before it can get near the fish, then measure pH after it has had enough time for complete distribution through your system- depends on pumping volume etc, but after 12 hours should be ok.

Yep trout make ph dip - shell grit has buffered my two systems throughout summer but now with trout it will go down - I've used dolomite - no where near as strong as builders line


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