gULP Filter Systems


If you haven't already, you need to read the page on Filtration Explained - it goes a long way into explaining why gULP is so special.

Else read on for everything else you can possibly want to know about gULP.

gULP on stand

Over the 'more than we care to admit' number of years that we've been players in the Koi industry in our own small way we have seen many filter systems come and go. We have seen seriously expensive innovations arrive with much fanfare only to disappear into the sunset as abject failures. We've been exposed to a few of them ourselves and we have had the wounds to lick. Please, if you are considering a sand filter, stop right now and read this.

We've also learned a great deal and we've been able to apply some common sense well grounded technical expertise to Koi pond filtration. Marrying technical know how with practical experience generally, we hope you agree, results in workable solutions to problems.

gULP Brochure (PDF)

After all, when it comes down to filtration and Koi ponds, it isn't actually about us at all. It's about YOU!

Our role is to try and guide you through why we think the gULP filter system is the best possible system for Koi ponds. It's up to you to think about it and decide for yourself why you agree with it or not. 

But as with all things in life, there is a lot to know before you can begin. As we have often stated on these pages, Koi keeping is fascinating hobby wherein to get it right first time is impossible. You need to know everything there is to know BEFORE you put the first spade in the ground on the way to your Koi pond.

The gULP filter system, we hope, will put you in a position of understanding it quickly. Once you have it in place and it is up and running, over time we hope that you come to appreciate just how good it really is and how much effort has gone into making it a one stop filter.

So let's get down to it!

gulp mould

All Koi pond filter systems do two things. They clean the water of mechanical debris such that we can see our Koi swimming in clear water (we call this mechanical filtration), and they also clean the water of dissolved waste, most notably ammonia, which is highly poisonous to Koi (we call this biological filtration). 

Hence all good Koi pond filters feature a minimum of two stages in the filtration process. A well built Koi pond will have a settlement chamber built as part and parcel of the Koi pond and it can be argued that this acts as a mechanical filter in it's own right.

However, the issue with Koi ponds is both with big floating debris such as leaves, acorns and the like, as well as the fine, small suspended stuff, called debris or detritus that is sometimes almost too small to be seen by the naked eye. This causes the water to appear cloudy and murky.

So your mechanical filter needs to be able to trap this fine detritus, without becoming clogged by all the big stuff and still managing to be easy to clean. There are a number of ways of going about this, all of which can be accommodated by gULP.

The second stage of filtration, the biological stage is most important. In your biological stage you want as little detritus as possible as any build up of detritus will negatively affect your bio filter's performance. When it comes to biological filtration people will tell you that you can use just about anything to provide a surface area for good bacteria to grow on and it will work.

In our experience, this is completely true. For a while anyway. It's after that, at some time in the future, that suddenly things go wrong in the bio filter and your collection of priceless Koi ends up stone dead in a single day. In short, yes, any media 'can' work in any particular bio filter. It's just that few of them 'do' work as intended and it can take years before the unintended consequences make themselves felt.

The fixation with 'surface area' is the big thing that seems to trap new Koi keepers. Surface area of a media in a bio filter is completely and utterly meaningless. Surface area means NOTHING!

If however you talk about ACTIVE surface area, then we have something we can work with. The sad fact is that up to 85% of all media in a static bio filter, ANY static bio filter is inactive owing to water flow patterns (and you can stand on your head and scream and shout at your filters, but your water sadly can't hear you!).

Further, static media suffers from debris accumulation. As the bio film dies and replenishes itself it forms its own detritus that is organic and which builds up in the bio media, fouling it over time. This is a concept called bio fouling.

Remember, bio filters need to be kept clean. Any media that can harbour detritus within it by settling or by entrapment is less than optimal.

Also don't be sucked in by that old hoary chestnut that surface area is the most important specification for bio media. It simply isn't true at all. If you have to worry about the surface area of your bio filter in your Koi pond, you're starting off on the wrong foot. Don't worry about it.

Whilst we're on the topic, you'll notice that we're vague about how much water gULP filters can treat. This is deliberate. It's pointless rating a filter on pond volume when one knows absolutely nothing about that volume whatsoever. What we can tell you is what amount of food our filters can handle, and what flow rates they can handle. It is these that are the important performance characteristics of any filter!

gULP Development

Over the years we've worked with just about every conceivable filter system available to KoiKind. We've seen filters built using crushed stone and voids. We've seen pressurised filters of every shape and form you can think of. We've seen more variations on low pressure (or open systems as we like to call them) than most. We've experimented with, tested, destroyed, evaluated and monitored more filter systems than anyone else we know.

We've come to two conclusions.

1. The moving bed has no equal in biological filtration. Nothing comes close in terms of size vs performance. Nothing. It is a staggeringly brilliant media.

2. Maintenance of your filter systems should be easy. It should be quick and it should take less than 10 minutes per bottom drain on your Koi pond (you need one bottom drain per 15kl of Koi pond volume). Hence a 30kl pond should take a maximum of 20 mins for a complete system flushing after which the entire filter system should be spotless.

You will find a lot of filtration systems promise this yet they only fail to deliver when it comes to you doing all the work! This is because you will find it is very difficult to achieve a spotless filter in under 10 minutes.

gULP distills everything we have learned into a simple easy to use filter package. We combined everything we wanted from a filter into gULP and we added a few things we didn't want for good measure. We chucked in a couple of optional extras to complete the recipe and the result is a simple filter that remains flexible to your requirements.


gULP on stand

From the picture above you should be able to see a couple of things immediately. Firstly, gULP is quite tall, standing about 1.3m from the ground to top of the filter. This is so that you can stand next to the filter and still have access to the internals of the filter for maintenance.

Secondly it is quite squat. This is to preserve acreage, or the foot print size of the filters when installed.

The most obvious of the pointy out bits are the 110mm connectors. There are two of them visible and there are another two on the opposite side of gULP. 110mm piping was chosen since this will allow maximum flow rates through gULP. You can clearly connect to the top or bottom of these, depending on what you want to achieve. It is also easy then to connect multiple gULPs in series or in parallel.

The 110mm connectors can be fitted with either standard 110m press fit plumbing fittings, or with two way rubber connector flanges.

So obsessed were we with making gULP as easy to install as possible we insisted on having flat sides. This is difficult to achieve with a free standing unit like gULP but we managed to get it right. So if you want to connect gULP at right angles to each other all you need is to plumb on a rubber flange onto the flat side (which prevents any possibility of leaking). These flanges come in 110mm, 63mm and 50m sizes.

The same goes for the large square sump at the bottom of gULP. This was made deliberately big enough to accommodate a 110mm flange if need be and the square shape means you can run your drain piping in any direction.

gULP has a flat section on the bottom on which the filter is supported. This can be done using the optional stand as shown or as something simple as a brick plinth. Once mounted gULP is entirely self supporting when full and it will not bend or warp over time. It will last a lifetime.

The four indents on the top round ring are in fact internal brush rack supports. These are spaced such that when brushes are fitted to gULP they are packed tightly together to ensure maximum mechanical filtration capability. gULP uses 400mm brushes which are relatively short enabling them to be cleaned from above with minimal effort. You can just chuck a bucket of water or two over them when the filter is empty to dislodge solid particulate matter to be flushed quickly and easily. Or you can simply hose them from above for a few seconds. That would be the total sum of weekly maintenance required.

The big round rings that run around gULP are in fact to support internal stainless steel shelves. In this fashion gULP can accommodate any media ever used on any Koi pond filter anywhere. You can stuff gULP full of SuperActiFlo the moving bed media, or bio balls, Alfagrog, Japanese matting, filter sponges, hair curlers - or whatever else may take your fancy.

gULP also ships with an easy to remove sturdy lid to round it all off.On the inside of gULP you can see the inner workings. The brush rack slots are clearly visible, as are the shelf supports. The sump and the flat bottom section that supports the filter are also clearly visible.

The 110mm connectors are initially oversized. This has been done to allow the fitment of small slotted stainless steel covering plates which are fitted when containing SuperActiFlo or any other light media for that matter. The oversizing means that flow restriction from the plate itself is negated.

And it still gets better. gULP is positioned to provide truly world class quality water for Koi. Yet it is priced aggressively when compared to equivalent conventional filter systems.