Flow Control of cannister filter

[jhseah]

May I know if I should control the flow of my cannister filter using in/outlet tap?

Pls advise

[bclee]

use the outlet tap.

BC

[vinz]

To add on to BC's post, only the filter outlet tap, never the inlet tap.

[|squee|]

[quote:24b1b92a0d="vinz"]To add on to BC's post, only the filter outlet tap, never the inlet tap.[/quote:24b1b92a0d]

Just curious, why is that?

I also heard that controlling fliter flow will spoil the fliter over time? Anyone can shed any light on this?

[vinz]

[quote:d8aa2f819f="vinz"]To add on to BC's post, only the filter outlet tap, never the inlet tap.[/quote:d8aa2f819f]

This is from the Eheim's FAQ. The eheim.de website is down at the moment, so I can't link to the article.

IIRC, the article does not explain why though.

[bclee]

When you restrict the flow at the inlet tube, you will cause the static pressure at the impeller eye to drop. This drop in pressure might cause dissolved gas in the water to form gas bubbles in the pump. This can cause cavitation and may result in:
1. loss of suction
2. fluctuation in flow
3. decrease in head developed
4. damage to impeller

For every pump design, there is a minimum continuous flow. As long as the flow is above this, it should not cause problem to the pump. However, for hobbyist's filter, this minimum flow is not quantified anywhere. Personally, I feel that one should not overly restrict the flow for the pump, e.g. restricting the flow to 25% of the design flow rate.

BC

[jhseah]

Thanks for the information.