more media in the basket?

[jarthel]

this is the 2nd basket on my 1200LPH canister. It uses porous noodles from Fluval. Looking at it, it seems half-full. I think it could fit another box (1.1Kg) of the media but it might be almost full.

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This is the 2nd basket of my 2000LPH canister. As you can see, I'm using plastic pot scourers. It seems I can still add another layer and they won't be packed tightly.

This is the 3rd basket on my 2000LPH canister. It's using porous noodles from Fluval. And there's plenty of room left. I've only put 1.1Kg of the media. I believe if I put 2 more boxes (2x 1.1Kg) on this basket, there's still plenty of room.

Do you still I need more media in the baskets I've shown? Bottom baskets on each canister contains a course and fine sponge pad. The topmost basket contains zeolite and wool pad. Thank you for the help

 

[dw1305]

Hi all,
If you ignore mechanical filtration, and assume that the sponges are being cleaned regularly and taking out all the fine material before it reaches the main biological filter material, the biological filtration ability of any external filter is dependent upon the volume of filter material and it's "effective volume", which is a balance between the flow of the water, the internal volume of the filter material, and how oxygenated the water is. This again depends on a number of factors, but unless you high flow and a relatively low bio-load, almost certainly some proportion of your biological filter media will be ineffective, as the water reaching it will have been de-oxygenated before it reaches it. This can be estimated from the total Biochemical Oxygen Demand (BOD), although even this is usually estimated by the "5 day BOD", and unfortunately this isn't something you can do outside of a lab.

So the answer to your question is that unless you have highly oxygenated water flowing through your filter you will probably have lower biological filtration with more media than you did when the basket was half filled. In the waste water industry (including Aquaculture), this is why they use trickle filters and fine bubble oxygen diffusers, when they are dealing with water with huge BOD values.

cheers Darrel