This morning I installed the the Ehiem.
First impressions: Build quality is if a VERY high standard. Design is by someone who knows what he's doing. Parts and filter media are designed to last, not be replaced. Oh and the impeller cover looks like it could hold in a port hole on a submarine.
I have plumbed it in using my existing Fluval hosing, which I found to be a good snug fit, I used the hose clip that came with the Ehiem to secure it to the hose connector of the filter. Looks good, will keep a close eye on it for a week or so in case of problems. My reasons for using the Fluval hosing are:
1. It is extremely flexible and will not kink.
2. The brackets that mount it to the side of the tank prevent the weight of the water filled hose from pulling fittings such as lily pipes out of position.
3. the only joints outside of the tank are where the pipes connect to the pump head. (reduced risk of leaks).
4. Its does not seem to get contaminated and clogged in the way that "standard" hoses do and so needs much less cleaning.
5. It has a larger bore than the Ehiem pipes and so should not cause any flow problems.
6. I wanted to be able to directly compare the output of the Ehiem to the Fluval.
7. The Ehiem hoses and fittings are green. No actually they are GREEN. (for the correct effect you need to SHOUT that last GREEN loudly, No louder than that. Louder!)
Flow is at least double that of the Fluval, possibly more. Of course it's all brand spanky new at the moment.
So how does it filter water?
First of all there is NO bypass. None, nada, zip.
Water enters the top of the filter and is drawn into the Bottom of the top tray, which is sealed off from the other 4 media trays, it then flows against gravity and though a coarse "pre filter" until it can flow down a triangular channel in the corner of the filter box, the opening of which is above the pre filter. (gravity trap, designed to take out any large/medium solids).
Once the water is at the bottom of the filter box it enters a void below the bottom media basket before being drawn very slowly, due to the large cross section of the media baskets, upward. (another gravity trap)
There are 4 media baskets. The bottom 2 are filled with "MECHpro", short sections of small gauge ribbed plastic tubing, designed to trap medium/small solids. These are completely reusable and washable. The third basket is filled with "bioMECH". Cramatic media designed to trap small solids and to provide some biological filtration. This is also washable. The last basket is filled with "SUBSTAT", a cramatic biological media, topped off with a large polishing pad. The biological media does not require replacement. It is recommended, by the instructions, that the polishing pad be replaced rather than cleaned. But you can clean it if you need to.
All in all I think that the Ehiem is going to work out much cheaper than the Fluval in the long term. (apart from the fact that it actually works)
Oh yes. it only does 16 Watts if electricity and no you can not hear it AT ALL.
So apart from the GREEN hosing and fittings.
Whats not to like?