Beware and be prepared ... Koi ponds and Spring

Spring is around the corner and for those of you not living in Cape Town (along with the free flush of your Koi pond via a few zillion cubic meters of rainfall) it's time to start thinking matters Koi. Cold weather and cold water slows everything down and gearing up for the warmer months is always an exercise that presents a few challenges.

SA is not what one would consider a cold climate destination. Our Koi should pull through winter with considerably less difficulty than our Koi keeping brethren in the UK. Our shorter winter, milder temperatures and of course superior Koi keeping skills, all combine to see off the nasty effects that prolonged exposure to cold temperatures inflicts on Koi.

As far as I can tell, most ponds on the Highveld probably didn't drop below 10 C for any significant length of time. But don't be fooled. You Koi's immune system is not infallible and right about now it is at it's most vulnerable. As the water warms up, bugs and other nasties start their activities much faster and sooner than your Koi starts it' immune system. It is NOT the time of year to dump massive quantities of good quality local Koi food down their throats in an attempt to fatten them up as fast as possible.

Rather, start increasing feed rates slowly. Rather more slowly than quickly. You will (or ought to) know the temperature of your pond and what it has been over the last few weeks and your Koi will tell you how hungry they are by their levels of activity. You will start to see these increase as the water warms up gradually - and you should increase feeding gradually.

This is where LOGS are so useful. Keeping a log of what was fed when and in what quantities to how many Koi of what size and at what water temperature is a useful tool. Remember my article on Koi pond water testing? Testing and logging is so important I think every Koi keeper should keep one - it also helps to share information and compare results with your friends. Think of it like a CSI program - history helps shape and frame a picture of your Koi pond.

This is also the time to beware the sand filter. If you still insist on running with one of these nasty things, start cleaning it more regularly from now on. Twice a week is about the minimum for one of these things - preferably every day if I were to have my way. Remember that bacteria and fungus sludge that congregates in these sand filters will do so far more rapidly as the water warms and can build up very quickly before your Koi's defenses are up to full strength. If you can avoid using your sandfilter as a mechanical filter (i.e. solids trapper) on your Koi pond it is a great idea to replace the sand with Alfagrog and Kaldnes. Kaldnes will work very well in instances where small solids are transported into the filter but even this 'wunder filter material' will not be able to handle pure unfiltered pond water with suspended solids in full flow.

Kaldnes is best agitated in a tank by air bubbles - the more Kaldnes the better and the more air the better. A good Kaldnes bio filter should look like the proverbial Witches Cauldron - on Speed. Lots of bubbles, lots of action and massive bio conversion.

I have often been asked, and it is a fabulous question - can I overstock/overengineer my Kaldnes bio filtration to the point where I need NO mechanical filtration? In other words, can I use masses of Kaldnes to break down my solids into ammonia and then from ammonia into nitrite and nitrate via the normal nitrogen cycle?

I have to answer that in theory yes you can. However, water clarity is likely to suffer as the solids that enter the bio chamber will be broken up and not all will be reacted by the Kaldnes on the first pass through the filter. This is unless you build a seriously big bio chamber which will cost you more than an Answer will in the first place. Kaldnes operates at best efficiency of between 30 and 60% density per volume although you can go lower than this depending on design. The Nexus for instance only gets up to about 35% when filled with 200l of Kaldnes but this is due to the efficiency of the design of it's chamber.

Further, it is not always a given fact that all organics will break down into only ammonia. You may get some organics peculiar to your pond (depending on food fed to Koi, plants, birds etc.) that may break down into highly toxic substances that are not broken down by your bio chamber. Unlikely though that is, I'd hate to be responsible for the death of any Koi as a result of a small oversight like this.

My advice is that is always FAR better to remove solid wastes from intimate contact with pond water. This way, if these solids break down into ammonia, toxic sludges or become disease infecting havens of bad bacteria, fungi, parasites and other pathogens, your Koi won't notice, let alone have to worry about these additional problems when building up their immune systems to peak operational efficiency. Remember, bad smells have no place in Koi ponds!
If you can dump these solids out of your Koi pond from the word go, whilst they are still 'fresh' and un-decomposed by bacterial action - so much the better. This is why sand filters MUST have regular flushings and regular agitation of the sand particles to slough off as much of these solid wastes as possible - get rid of the food source for all the nasties that we DON'T want in our Koi ponds.

So when starting off I think it best to listen to the experts and trust the success of systems that have consistently proven themselves. I don't think it's fair on Koi to experiment on them - although if there are experienced Koi keepers out there that are willing to experiment on a controlled basis I'm happy to chat to you. Perhaps in conjunction with Ozone such a filter may well prove successful. This is part of what makes up a fascinating hobby.
To those who have and are building stunning ponds (Roland, Tim, Deon, etc.) and others of you who have ponds - please submit me pictures of your ponds - I would like to start a portfolio of inspirations for Koi newbies/wannabes - include pictures of yourself and other people where you can. Be warned - no Koi abuse (such as kissing them on the snout) will be published! Don't forget that Rob the Pond Builder of note is on hand to help us help you with building a Koi pond/sorting out problems - even if he is a little overloaded at the moment he still manages to get around to helping us out. After all, as I say, his sleep is over rated...

Go carefully, keep a close on your Koi, log everything and enjoy! Summer's almost here and Koi enjoyment time on the horizon. Article by William Kelly