Backyard Aquaponics
A place to discuss aquaponics

Hi Mike,
I am in Greenwood. :-)
The koi was given to us by a colleague. She inherited the koi when they purchased the house.

I emptied my tanks, cleaned my pumps and filters, sprayed all surfaces of the tanks etc with a very strong Hydrogen peroxide solution and wiped them down. Refilled the systems with clean water and added Hydrogen Peroxide into it, then ran the systems for a few days, before draining and refilling them with more clean water. I also cleaned down and sterilised anything that had come into contact with the system, ie: pH meter, measuring jugs, water sampling containers etc.

In your case I wouldn't panic and go to that extreme at this point. There's only a slim chance the prawn did introduce something nasty, I think we were just extremely unlucky in our case. I've got a Murray cod in a tank next to where the yabbies were, she is around 12 or 13 years old, been fed on the same River prawns (that's why I had them) and she's fine.

My comments were more to point out that there are much less risky, more beneficial (ie: Seasol providing nutrients for seedlings as well as Ammonia) ways of cycling a system than using something dead and rotting. Plus I was curious who it is that keeps telling people to do it.

Many people do give new fish a salt bath prior to adding them into a system. I've added fish with and without doing it. When I've done it I've calculated the volume of water in their transport container (large esky) and added salt at 10gm/Ltr, then left the fish in there for 2-4 hours. You have make sure the volume of water is sufficient that it won't see too big an Ammonia build-up, and you also have to ensure the water is very well aerated when salt bathing.

The Ammonia levels won't "spike" when fishless cycling... You control the Ammonia level with the daily additions of Seasol Powerfeed. When it reaches the desired level of 1.0pp - 2.0ppm you stop adding it.

Nitrite will spike, usually about 2-3 weeks after adding the Ammonia. This will occur as your Ammonia levels begin to drop. The Nitrite spike in most cases reaches about twice the level the Ammonia was, ie: 2.0ppm of Ammonia can result in a 4.0ppm Nitrite spike... but not always, sometimes it's much less, depending on how the cycling process is progressing, water temps etc.

Absolutely!... That's the whole idea behind cycling without fish in the system... So you can ensure the beneficial bacteria colony has developed sufficiently and the system is safe for your fish. Once both the Ammonia and Nitrite have dropped to 0.0ppm the system is considered cycled and safe for fish.

It was at the time, we lost hundreds, possibly thousands of them... It was hard to watch the poor little buggers dying every day.

I really appreciate you time and wisdom Mr Damage....

I feel a lot more confident in cycling my system!!

Different stories all over the web.
We have started our system with the fish in the tank and plants in the grow beds.
No issues at all.

Just letting nature run its course...can't go wrong with that

You certainly can cycle a system using the fish as the Ammonia source... under certain conditions.

Ammnonia becomes more toxic to fish the higher the water temperature and/or pH, so cycling a system in the cooler months with trout fingerlings for example, is very feasible here in Perth, many have done it. But cycling a system with fish in Spring or Summer is just about a guaranteed recipe for disaster.

As an example, if you look on the Ammonia Toxicity chart below you'll see that at a water temperature of 28ºC and a pH of 8.2, it only takes a whiff of Ammonia, 0.2ppm, for it to be harmful to your fish. The first measurable increment above 0.0ppm on an API test card is 0.25ppm, so even by the time you got an Ammonia reading it would already harming your fish... and it's not uncommon for Perth water to be a pH of 8.4 and have a water temp in Summer of 30ºC, even 32ºC, in which case it would take even less Ammonia to start harming your fish.

Cycling without fish is definitely much less stressful, for you and the fish.

Plants, they can go in from day one.

Whoops!... I thought I uploaded the Ammonia Toxicity Chart image... I mustn't have clicked "add file" or something???

Anyway, here it is:

Mr Damage,

May I just clarify about the bath salt ratio?

Was it 10 grams per 1 Litre or 1 gram per 1 Litre (1ppt)?

1gm/Ltr in the system if salting for a Nitrite spike.

10gm/Ltr if salt bathing fish prior to adding them into the system.

With salt bathing, always ensure there is a LOT of air going into the water. I like to leave them in the salt bath for 4 hours if possible, but if they show signs of distress before that, get them out and into the main system. Also, check the Amm level every hour or so, it can build up quickly with a high concentration of fish in a small quantity of water.

Cheers mate!

I'm a little curious to this cycling process as well because everywhere I've looked nobody really explains that if I do fishless cycling can I add my tank capacity once the the tank has stabilized and plants are all in position or should I slowly add them I get the whole cycle process I understand that I would just rather cycle without fish then add them all at the end if possible

And if I were to cycle with fish would I want to start with half capacity or can I run it with all the fish

My setup is 10 grow beds made out of 55 gallon drums (cut in half) and 275 gallon IBC tote

Also would I benefit by running a bio filter with some type of media i.e. K1 or something to that extent to promote the growth of bacteria and what do you guys think about speeding up the process with some type of nitrifying bacteria in a bottle

Here's a plot (see pdf) of where my system went during cycling.
And the toxicity levels (the colored lines are the same as Mr Damage's table)
The red dashed lines are the EPA toxicity criteria. The topmost is 50% dead in 1hr, the other dashed lines are for 5% dead in a month.
Note that lowering the pH is more significant that lowering temperature.

Oops , the graph didn't attach properly.