Backyard Aquaponics
A place to discuss aquaponics

So, I'm trying to cycle my system and I don't seem to be getting anywhere. I'm not sure if I'm expecting too much, doing the wrong thing or if I've missed the boat and my system has cycled itself while I wasn't looking.

The System
2 chop and flip IBCs connected and using a mixture of scoria and expanded clay balls in GBs. Flood and drain has been occuring for about 6 weeks. I introduced around 20 little fish (gambusia) and about the same quanity of little shrimp from a local creek about a month ago. They appear to have been mainly grazing on algae, a weekly teaspoon of leftover catfood and possibly some of the stuff I've added to try to kick start my nitrogen cycle. Around 2 weeks ago I planted the beds.

My Attempt at Cycling
About a week ago I added 2 dried green lip mussels and some fresh scraps of chicken (amounting to the size of a green-lipped mussel). After about a week, my Ammonia rose from zero 0.25ppm and 0.5ppm over 3 days. It then went back down to 0.25ppm after a day and has now returned to zero. I've had zero ppm for nitrates and nitrates all along. The mussels are now nice and furry and floating and can be smelled from a few metres away if downwind. I did read somewhere about using a seaweed extract fertilizer (seasol) as an ammonia source and put three capfulls in a couple of days ago but still nothing.

Other Things Perhaps Worth Note
[*] My PH has been up around 7.8 mostly and despite three attempts to lower it with hydrochloric acid, bounces back after a day.
[*] Many of my seedlings have had one or two of their outer leaves yellow and wilt but otherwise look healthy
[*] I only started measuring my amonia, nitrates and nitrates about a week ago when I added the mussels and chicken to kick things off.

Is there anyone with a bit of experience please who can let me know whether I'm on the right track and what may be going on with my system?

Sounds like your system is probably cycled but go easy on feeding until it's matured a bit more. You don't say anything about the size of the system so it's tough to tell what to expect from this number of fish.

Which version of Seasol were you using?

Why would you???...

The mussels might be furry, but it's far from nice... It will be saprolegnia, a fungus that can transfer to fish.

As you have read, probably the easiest way to cycle a system is to add Seasol Powerfeed (green bottle, not the standard Seasol), at 1x capful per 500L per day, testing the Amm level 24hrs later. Once the Amm reaches somewhere between 1.0-2.0ppm, stop adding the Powerfeed and keep testing the Amm and Nitrite daily. Once the Amm drops to 0.0ppm and the corresponding Nitrite spike has also peaked and dropped back to 0.0ppm, the system is cycled... Simple as that.

You can use other sources of Ammonia, such as pelletised urea, but the Powerfeed is probably the best option IMO, as it it not only provides the Amm for the cycling process in a cheap, easy, controlled manner, but also enables any seedlings to get a head start. This way the plants are well established when the fish go in, so they can keep up with the corresponding increase in nutrients.

If you added fish and shrimps a month ago, they would've been releasing Ammonia and the bacteria colony would've started developing from there. After a month it most likely would've been cycled, which bears out with your comment about seeing an increase in Amm and then it drop to 0.0ppm...

You're system is cycled!

P.S... A pH of 7.8 is fine for a new system, you will still get healthy plant growth at that pH, provided there are sufficient nutrients going in the system. So once the fish are added you should use a good quality fish food, such as Skretting, and a capful of standard Seasol (white bottle) per 500L per week.

Adding fish safe amounts of acid (ie: no more than a 0.3 pH drop per day) directly into the water in system with a high pH, which is usually caused by high carbonates, will achieve almost nothing, it will bounce right back up within hours and you would need to do this many, many times to consume enough carbonates from the water to start to see permanent results.

The pH will naturally drop on it's own over time. It could start happening within weeks, or could take months, depending on the carbonate level in your system water, type of water used for top-ups, and level of Nitrification taking place in the system.

Thanks scotty435 and thanks Mr Damage

Why would I???
I think the short answer is ignorance on my part.

The internet is both a blessing and a curse. I read so many different bits of advice on how to cycle (including allowing fish, prawns, etc to rot) that just picked an approach and went with it. I also managed to miss the detail of Powerfeed rather than standard Seasol.

Thanks for the tip on the saprolegnia too. I'll be cleaning out anything on the bottom or surface of my FTs tomorrow and anything furry will be getting a decent burial.

Am I right in thinking that a cautious approach now would be to continue to add a few more shrimp every week or so until the load is similar or more than what I'll have on introducing the jade fingerlings. This will give my plants a chance to hit their straps and the bacteria in the beds to flourish for a while longer. Also might mean I'm putting the Jades in as the weather starts to warm up, which I'm guessing will be best. Before I get the jades, I can transfer some of the shrimp into my duckweed tanks and either return the remaining shrimp and the gambusia to the creek or use them for protein.

If we think I've cycled, do I continue to use HCl to bring my pH down by degrees?

Once again, very much appreciate the time taken to provide detailed feedback. Cheers.

@Mr Damage - You must have posted whilst I was still composing my post

What you're describing with the pH is exactly what I've been seeing.

One thing I didn't mention is that without a heavy load on my system so far and the cooler temps, I've only been relying on the drain of my GBs for aeration. I'm hoping to get my air pumps set up this weekend. Will this additional aeration help with the pH?

Top-ups will be with rainwater from poly tanks which tends to be a bit acidic, so I geuss this will also help.

Thanks again.

What does "fresh" mean? raw?

When using decaying things to cycle,you could introduce dangerous bacteria & pathogens into the system.


You keep saying Nitrates,what about Nitrites?.The Ammonia will go down once Nitrite goes up,but it's still not cycled until Ammonia & Nitrites are at 0 and Nitrate is up.

Mix the rain water with your tap water & find the magic ratio.Try for a PH of 7 & a KH of 6 (drops),