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905-715-2447 Winter Hours: By Appointment Only 3301 Sideroad 10, Bradford, ON Canada
This entry is part 2 of 4 in the series The reversed sieve

IMG_0035In my last blog about the Criel sieve I explained the functionality. Someone asked me the following question: Is it possible to make a inverted sieve in a round tub? I struggled with this for a while, but I can answer the question now: yes, it is possible! In this blog I will explain this to you.

Also someone gave me a critical remark, which was justified. The pictures in the articles were not correctly. At the moment when I was demolishing my old filter, I remembered I still had to take photo’s. I placed back the sieve in the first filter chamber and forgot in the hurry I misplaced the sieve! My apologies if I have put you in the wrong way because of this. Of course I made new pictures for the article and already replaced them. Only the sieve in the first filter chamber is still wrong. This one is demolished so I cannot make new pictures.

“It is about the point that you must be aware of the fact that a Koi pond should be filtered well and rinsed regularly”

To get back to the question. I will try to answer the question by giving you an explanation and show some photo’s. The photo’s are given to me by Martien Claessens, moderator of the Koivrienden.be forum. He has created one of these sieves in a round tub. After I decided to remove my ‘one cubic metre’ basins I came in a sort of time trouble and needed new filters for my pond quick. I bought three second-hand 300 litre square basins and one 310 litre round basin. I wanted to use the round basin as a vortex. However I already figured out the excising Criel sieve wouldn’t fit in it because of the connections.

I didn’t have the time to think for a solution because it was half September already. I decided to fall back on the filter brushes. Lots of you do not like it because of the cleaning. I have to say it goes well on my way, I’m cleaning them daily. I just close the supply pipe and the transit pipe and start to shuffle the brushes through the water in the basin. After this I drain the basin through a 110 mm pipe. This is how I do it at the moment.

Because of this, I easily have my 10% weekly water changes which are necessary to get rid of the nitrate in a Koi pond. You already knew this but I’m still saying it because it is really necessary.

I will create the new situation of the Criel sieve next year on Martien’s way. I will have to create a new holder like this one:


Sieve holder for a round tub

You can see that the bottom side is right-angled, filled with the space of the curves that the round barrel has. This way I can seal the holder, so the water can only come in through the sieve. The only challenge is to measure it, but that’s possible. Martien used Perspex as frame, but I will use Volker plate. It is not necessary to use Perspex and it is possible to use other materials such as Volker plate.

In my design I have milled slots. Martien used a aluminium profile, which is a really good solution in my eyes. Both solutions work, but I say this because there a more ways that lead to Rome. Of course it is needed to make a pipe with 1 mm holes to keep the sieve clean.

The result will look like this:


Aluminium profile that Martien uses


Round tub with inverted sieve in use

Because of the transparency of the holder it is possible to see in the above picture that it is simple to fit it in a round tub. Also there can be proven that it is not necessary to use a huge collection chamber. You can also see the air bubbles in the picture that are created by the air tube on the bottom of the sieve.

After all the Criel sieve is a way of filtering which you can like or not. I choose for this way, because it is a really energy efficient way of filtering. Others maybe dislike it and prefer a bead filter, others prefer a combination of both filter systems. There are a lot of combination.

It is about the point that you must be aware of the fact that a Koi pond should be filtered well and rinsed regularly. If you don’t, you have to ask yourself if you would like it when someone locks you up in a glass box, where you can only take a shower once a month and where you can only flush your toilet once a month, but you still get your daily meals. Put this idea over to the Koi pond in your backyard. Where you have exactly this situation!

Good luck in considering which filter line to use.

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