# ideas for a pre-filter



## Paulus (9 May 2016)

Hi,

I have a nice pond with goldfish in it. i also have a Velda Cross-Flow Biofill filter on it.




 

But the first chamber with japanese matting is always pretty dirty. Result is less flow inside the filter and a mess when cleaning 

So i was thinking for a pre-filter. Because of the small space (and money) i can't use or buy a sieve they use on koi ponds. So i need something smaller to collect the dirt before the water reaches the filter.

here some DIY masters that made a pre-filter out of a simple bin/plastic box etc? or experience with the best results?

I am thinking of a simple plastic box with inside a plant basket and a bag. So the inlet is inside the box and outlet connected to the current filter. This idea but in a box:


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## martin-green (9 May 2016)

What ever you do decide to do may I suggest that the filter medium is no higher than half of the box. The reasoning is that if it becomes choked the water will still flow but over the medium and not over the sides of the box


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## Paulus (17 May 2016)

Saw another interesting concept which i give a try once i collected all the pvc parts etc 



if it doesn't work i can re-use the PVC for a new setup/test


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## Easternlethal (17 May 2016)

I'm not sure the sequence of filters is right. UV should be the last stage with the coarser filter nearer the intake and finer filter nearer the outflow. At least thats how I do it in a canister.


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## martin-green (17 May 2016)

Paulus said:


> Saw another interesting concept which i give a try once i collected all the pvc parts etc
> 
> if it doesn't work i can re-use the PVC for a new setup/test



Good luck, why not take pictures too. 

A word to note: If his filter blocks it will not matter...........it was sitting above his "pool"


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## Paulus (19 May 2016)

Easternlethal said:


> I'm not sure the sequence of filters is right. UV should be the last stage with the coarser filter nearer the intake and finer filter nearer the outflow. At least thats how I do it in a canister.


I see different setups that are used. UV before and after the filter. Some say before the filter will kill the algae and traps it in the first chamber of the filter and others prefer after the filter to collect the large stuf first and than use the uv in clearer water.

Don't know which would be the best but i can't change it anyhow with the current filter (and i haven't used the UV yet )


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## frederick thompson (28 May 2016)

Hi mate. On my koi pond. And my new build.i always have had my uv after filter. If you look at my thread. Freds new build. I am just having the plumbing done over the next ten days. On mine it goes pond to filter to pump to uv to upper pond return. And on skimmer line. Sieve to pump to uv to bottom tangible returns in pond. Also that filter bucket.why dont you try putting some micron mesh in side and run the water through that. Then you have made a sieve. Like say 58 micron and that will gather the fine stuff. But you would have to run the water through it. Like my ultra sieve does. Hope this helps. And best of luck mate. Fred


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## Paulus (29 May 2016)

Still thinking about which type of prefilter it will be. The current and running filter uses the uv as first step and i cant change it. Maybe when i rotate the top/lid. will give that a try . 

But i got a new idea (one i can find some bulkheads here -.- ). I have some round plastic planters like these. 



 

So i buy an extra one 
And i need to visit ikea for this product: stabil.

http://m.ikea.com/nl/nl/catalog/products/art/10112530/

Yes i can make a sieve (i hope)


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## frederick thompson (29 May 2016)

Nice one mate. Your uv will still work to an extent
But it works 100 percent better after filter best fred


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## zozo (29 May 2016)

Nice pot Paulus, but if you like to copy that swirlfilter idea, depending on the bulkhead diameter you might get into trouble with the bulkheads seal leaking..  Because the thicknes of the pot, my guess is it will stay curved no matter with how much force you tighten the bulkhead. The bulkheads are contstruted for sealing a flat surface. A simple bucket has i thin enough wall to be deformed by the thightning force.

If it's the velda filter with the 40mm inlet i think it is, you would need 40mm bulkhead on the pot to match the flow speed.. The bottom one on the pot is not going to fit i'm afraid since it has a much smaller diameter than 40cm. Next to that the pot's wall is inclined the bulkhead will point downwards to the ground once connected.

In these small dimension and if it needs to decorative as well i think you're better off finding something square and with flat surfaces.


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## martin-green (29 May 2016)

I would say that pot is far too small to be of any use as part of a filter, and also too awkward to connect a pipe to because of the angle.
If you are trying to make a vortex filter (One where the water moves in a spiral and so dirt falls to the bottom)  you need as big a diameter container as you can get, the reason is the water has to flow slowly, so that the dirt falls out, if the water is fast the dirt will be carried along with the flow and never fall out.


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## Paulus (5 Jun 2016)

The first parts are in and made a quick test setup to test the ikea part of this story  and it is collecting dirt


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## Paulus (26 Jun 2016)

New test setup


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## zozo (26 Jun 2016)

Looks great, why not fill it with small lava grit and put a plant in it??


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## Paulus (20 Jul 2016)

zozo said:


> Looks great, why not fill it with small lava grit and put a plant in it??



This is easy to clean without plants and rocks  all the lava etc is inside the big filter below.
And all the dirt and crap is:


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## zozo (20 Jul 2016)

Paulus said:


> And all the dirt and crap



That's what the plants would love and live of.. You will have a top notch biological filter.. I filter about 250 liters terrace pond like that.. Pump the water on top af a plant basket filled with substrate.. Pond stands in full sun all day, it's crystal clear and the plant basket with grassy plants like Cyperus and Rotala and few others grows like mad... 

You still can make it 2 steps, a plant basket seperate above that pot. So plants in substrate instead of the sieve..  It will sieve even better when it seeps down into the substrate.


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## Daveslaney (11 Aug 2016)

Static K1 makes a great pre filter,You can use any container with a drain to waste covered with a grid to stop the k1 going down the drain. To clean it you just fluidise it for 5 mins to release the dirt drop the water to waste.Job done.
Just like in a nexus.


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## frederick thompson (2 Oct 2016)

Like it mate .that's like a mini mini ultra sieve. I have a ultra sieve 3 on my skimmer line. And looking at that video does the same job. Is that mesh steel mesh or a type of nylon. And what micron size is that. Why I ask does it take the finest out.and not just solids. My ultra sieve is 100 micron in size. My rotary drum is 58 micron
I like your way of thinking. Nice one mate best fred


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## Paulus (4 Oct 2016)

frederick thompson said:


> Like it mate .that's like a mini mini ultra sieve. I have a ultra sieve 3 on my skimmer line. And looking at that video does the same job. Is that mesh steel mesh or a type of nylon. And what micron size is that. Why I ask does it take the finest out.and not just solids. My ultra sieve is 100 micron in size. My rotary drum is 58 micron
> I like your way of thinking. Nice one mate best fred



its a steel mesh/splatter screen from Ikea 

http://www.ikea.com/gb/en/products/...splatter-screen-stainless-steel-art-10112530/

No idea what the micron size is


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## sciencefiction (4 Oct 2016)

Paulus said:


> I see different setups that are used. UV before and after the filter. Some say before the filter will kill the algae and traps it in the first chamber of the filter and others prefer after the filter to collect the large stuf first and than use the uv in clearer water.



I think the idea of putting the UV at the last stage is because dirty particles in the water reduce the efficiency of the UV filtration.


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## frederick thompson (4 Oct 2016)

I use mine after the filters mate. My water is gin clean. My system on both lines go from bottom drain 4 inch line. to rotary drum to nexus to dry pump to uv  back to pond. My other line is skimmer. To ultra sieve 4 inch line to dry pump to uv  to mid water return jets. Reason for uv after filters is no big stuff ends up in uv s. My set up works. I also have upper pond with plants. This acts also as filter. Good system for fish. All the best fred everyone has different opinions. On where to put uv. Like in pond pumps. And outside dry pumps. Is two reasons to differ.  Best fred


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## frederick thompson (10 Oct 2016)

Most koi ponds have it as the last mate. and i have for 18 years. works for me and thousands of koi keepers. a lot has to do with where pumps are situated. But if you think it is better else where put it there. best advice is build a pond in the shade. then you do not need uv. best fred


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