Leaf question

[sinbad]

Hello all, am new to ponds and have a small pond up and running, I,m guessing that it's just over 1300 litres but it's very difficult to work out as its an unusual shape. At it,s deepest it is around 80cm's deep but there is a lot of shelf area which means there is alot of surface area, probably 2.5m x 2m.
I don't have alot of space in my garden and was aware that putting a pond under a diciduous tree can cause problems with falling leaves in the autumn. Well due to the lack of options i soon realised that if i was to have a pond then it would have to go under a cherry tree. I have a reasonable filter and my plan was to cover the pond with netting for leaf drop time. I've been running for about a week now and heres my problem, I thought i would get away with covering with netting for about a month in october / november time but this tree has been shedding constantly since early august, something i hadn't noticed before.
So how many leaves do yo think the pond and fish could tollerate before the water turned too poisonous?
I know it's difficult to quantify things like falling leaves but would be very inerested to read anyones thoughts. The obvious solution of course is to net up now but I'd really like to leave it as long as pos. I'm still showing my new pond off after all.
Thanks for reading.

 

[sinbad]

by the way, thought i should mention that i don't keep koi, just a few goldfish and comets

 

[sissy]

You could get a pool net or small net and everyday or so clean the leaves out if you leave them on the bottom they will decompose faster if it is warmer and could kill your fish .Most of us use swimming pool net ,but you could use something like a fishing net for smaller pond .I even use a long handled indoor tank net to get into corners to clean .

 

[Waterbug]

You're right, hard to tell. I had a pond that had a heavy leaf issue, no filter, no cleaning for 4 or 5 years. There was a decomposing mat of leaves about 6" deep on the pond bottom. Chunks started to break off and float to the surface for a while and then sink back. Pretty ugly so I decided maybe I should start cleaning the pond. Cleaning of course stirred stuff up. No fish died.

Pond keepers would be concerned about two main issues, increase in harmful bacteria and hydrogen sulfide gas.

The bacteria, like Aeromonas hydrophila, that eats dead organic in low oxygen conditions is also one of the flesh eating bacteria you hear about on TV sometimes. These bacteria exists in all ponds, but increased dead organic matter means more bacteria. However, just like people fish have ways of dealing with these kinds of bacteria and so normally they aren't a problem. When fish are stressed because of other poor conditions their immune system can be weakened, just like people, and then bacteria can be more of a problem. There is as a time, called "Aeromonas alley", of temperature in the spring when fish immune systems are just starting up but the bacteria is growing that fish as more at risk. Some people, normally high end Koi pond keepers, want as clean a pond as possible in order to lower the number of bacteria to in theory lower the risk. Whether the risk is actually lowered is unknown. But, they keep their ponds clean for many other beneficial reasons which keep fish strong and no doubt better able to fight off bacteria.

Hydrogen sulfide gas would probably be the issue most water garden keepers would be worried about. It's the gas that caused the chunks of dead leaves to float in my pond. The gas is toxic to fish, it's toxic to people too. However a certain level is needed to be dissolved in the water to be toxic. When people smell the rotten eggs they're breathing in hydrogen sulfide they're breathing toxic gas, but not at a level they die. Many people in pond forums get very animated about dead stuff in ponds and swear your fish will be dead the instant a leaf hits the water. Clearly things aren't that bad. Also clear is many fish have lived in these types of conditions long before humans were around and will long after we are gone. Fish can deal with a certain level of hydrogen sulfide and also it's not that easy to get a high level of hydrogen sulfide dissolved in water. Normally most of the gas is trapped in the much, so not a problem. When released it goes the surface and escapes into the air so little stays in the water.

So it's kind of up to you to determine what kind of pond you would like. People who keep a Wildlife pond very much want a layer of decomposing leaves in the pond bottom because that supports a system of bugs which the fish eat. People with a high end Koi pond don't want a single leaf in their pond because the O2 consumed in decay is O2 the Koi could have had. Water Gardens are generally some place in the middle.

What I've done in the past for small ponds is use a minnow net from the pet store to scoop out leaves and other stuff every week, or even every time I feed the fish. Takes just a minute or two. This removes stuff but also stirs the bottom which increases O2 down there which speeds up decay of the tiny stuff I miss because it's too small to see. The result is a very clean pond. Small ponds have many downsides but easy cleaning is an upside.

 

[sinbad]

Thanks for replies.
Sissy, I do use a net and will continue to do so. I suppose that i just needed reassuring that I wasn't being too neglectful, thanks
waterbug...wow, what a reply, you really seem to know your stuff! What you say makes complete sense to me and i feel confident that my fish will survive

 

[sissy]

good luck and happy ponding

 

[Waterbug]

I forgot to add...one downside to some kinds of leaves is the release of tannins. Same deal as tea leaves making water brown. Depends on the type of leaf. But if you do notice the water becoming more like tea the leaves could be the source. I doubt cherry leaves are a problem, but don't know. Tannins is not a big problem for fish.

 

[victoria.]

You could get a pool net or small net and everyday or so clean the leaves out if you leave them on the bottom they will decompose faster if it is warmer and could kill your fish .Most of us use swimming pool net ,but you could use something like a fishing net for smaller pond .I even use a long handled indoor tank net to get into corners to clean .

Does leaf matter release some sort of toxicity for the Koi?

 

[Mmathis]

@victoria. Hey, this is a very old thread, but yes to your question. Any decaying material can be “toxic,” depending a lot on the filtration you have. Think hydrogen sulfide!

Why not go over to our “introductions” topic and tell us about your pond?

 

[sissy]

built up leaf matter and fish poo can lead to fish death