Advice needed on filter media

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john5555leonard
Lemon Shark
Lemon Shark
Posts: 37
Joined: Sun Oct 10, 2010 7:22 am
Location: thailand

Advice needed on filter media

Post by john5555leonard »

Iv got a 7250 g pond with home made concrete filter,which consists of a vortex with brushes then 3 bays each 1mt square and 1mt deep , first bay is a plastic honeycomb cartridge with nets on top , second bay is bio balls last bay is gravel , my water is murky , it's ok down to 1mt but can't see the bottom , the bio balls are clean , not even developed a film , but last bay ( gravel ) is always dirty , I'm thinking of using jap mat in second bay instead of bio balls and k 1 in last bay . What do you think , would it be better to use k1 instead of jap mat ( it would be a lot cheaper ) it's been set up for 8 yrs and jap mat and k1 were not available then , we are a bit behind in Thailand . Iv never had a problem biologically just clarity . Hope someone can help , regards John
Manky Sanke
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Re: Advice needed on filter media

Post by Manky Sanke »

John,

I'm always a bit wary of gravel (or similar) as a biological media because it traps fines which either decompose or, worse still, clog it making anaerobic areas which can become a breeding ground for harmful bacteria. The fact that it's always dirty confirms that you are trapping fines.

Assuming your problem isn't algae, in which case you need a UV then here is my suggestion.

You could consider replacing the gravel with either Jap Mat or aerated K1, both are good types of biological media but neither will improve your clarity. An easy and effective way to improve clarity is to use filter wool. If you aren't familiar with filter wool the method is simple. Just lay a single thickness somewhere convenient in the filter so as the water flows through it, ideally as near as possible to where the water enters the filter and with the water flowing onto the top of it and in a downwards direction. This will trap fines and can be regularly rinsed to clean it for as long as it's serviceable and replaced when it isn't. Depending on where the filter wool is in your system and if you have a lot of fines to remove you should consider what will happen if the filter wool clogs completely. Don't use it in such a way that it can cause the bay to overflow or subsequent bays to run dry. The usual way is to lay it in such a way that, if it clogs and water can no longer flow through it then the excess water can flow past it or over the edges.

In case that description isn't clear, I've made a quick modification to one of my existing drawings to illustrate what I mean. It isn't meant to be an interpretation of the filter system that you have but it should show what I mean.

Image
john5555leonard
Lemon Shark
Lemon Shark
Posts: 37
Joined: Sun Oct 10, 2010 7:22 am
Location: thailand

Re: Advice needed on filter media

Post by john5555leonard »

Thank you
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