Walstad Goldfish Tank Update August 2009
It’s been an interesting few months for my Walstad goldfish tank. I’ve had some fish losses, plant additions, aquascape alterations and some have developed some ambitious plans for the tank.
Here’s what the tank looked like early July:
As you can see the plant at the front, which I believe came as a hitchhiker with some other plants has grown completely out of control and is not a suitable for the foreground. I also started to notice my stem plants, particularly the ludwigia in the corner and to a lesser extent the wisteria in the middle had started to become ‘leggy’ (ie. they were turning into leafless stalks with a bit of growth at the top).
Algae also gradually seemed to get worse and I even had a mini bloom out of noweher of the green variety mid July which I wasn’t too happy about.
I started to think about why this was happening and I’ve reasoned that with the canister filter running, the canister bio bacteria were probably out competing the plants for ammonia and nitrite. Then the nitrate was being consumed by the algae faster then the plants could absorb it.
I didn’t have any fast growers in there so I ordered some plants from livefish.com.au and have now have planted them amongst the established plants in there. I’m going to play survival of the fittest and keep whichever ones dominate.
To combat the nutrient problem I’ve decided to cut out the bio bacteria altogether.
Yes you read that right, I plan to run my goldfish tank without a filter.
Anyone who has kept goldfish will tell you they are masters of water pollution so I’ve set myself up for a nervous few weeks of water testing ahead while I ascertain whether the tank is up to it or not.
I’m also a little concerned about how the carbonate hardness of the water will hold up but with a drastic reduce in the bacteria biofilter eating up kh hopefully it stays high. The soil is mixed with crushed oyster shell although with little water movement down there I doubt it will do much.
If all goes well the bulk of the ammonia produced will go to the plants (a little will be processed by the tank bacteria) as well as any nitrite produced. Plants prefer ammonia and nitrite over nitrate so they should hopefully have no problem out competing algae for it.
Currently I’m also running it without a powerhead to see how that goes. So far I haven’t had any oxygen issues, I’ve increased the lighting duration back to 12 hours and have gone back to my starting watts per gallon of 2.4 (up from 10 hours of light and 1.6wpg over the last 2 months).
My next update will be at the end of August with hopefully good news.
Finally, since my last update I’m sad to report that Patch passed away. Swimbladder must have got him in the end. He was eating and behaving normally till he died so at least he was somewhat comfortable.
I also lost the big black unnamed fish I got due to dropsy. The onset of this was drastically sudden, I remember noticing his scales pineconing one evening at feeding time and over the next five or so days he lost his black colouring for silver/white. After he started floating near the top I figured it was time to put him out of his misery.
I’m assuming the sudden loss of color to white had something perhaps to do with internal organ failure. Why this happened I have no idea but it was painful to watch.
If the tank goes well over the next month I’ll look at replacing them sometime in September which will nicely co-incide with the goldfish breeding season! Anyway, here’s a snapshot of the tank as it is at the start of August (note the slightly cloudy water as the in-tank bacteria adjust to life without a filter colony):
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