Herbie overflows and gravity fed skimmer?

[Dale]

Hi Tony,

You can get away with one pre skimmer valve if the overall flowrate is strong enough but for the cost of a valve you will be much happier with the tuning ability of a two valve setup.

This is for a single overflow.
The problem is how to get a predictable flowrate to the skimmer without impeding the displays ability to drain (so the return pump doesn't overwhelm the overflow because of restriction). I have put a "step" in the overflow line to force the water flow first to the skimmer and then allowing it to continue on to the sump. You need a valve pre skimmer to control the flow rate into the skimmer. This, combined with the step will provide a constant flowrate in the skimmer but you won't actually block the overflow. You then need a valve post skimmer to fine tune it.



For a two overflow setup, just dedicate one overflow to the skimmer and the second to drain straight to the sump. Set it up so the first drains sooner than the second. That will provide a constant flowrate to the skimmer without risking a flood.

What you should not do is plumb a single overflow through your skimmer only. If the return pump was stronger than the restricted skimmer flowrate the display would back up and flood and.. if the return pump was weaker than the restricted skimmer flowrate you wouldn't be able to tune the skimmer effectively.

Hope this helps

[Delphinus]

Thanks!

What's the consensus regarding recirculation style skimmers anyhow? The one thing that strikes me as maybe a question mark ... if the skimmer was fed ONLY via the overflow of the main display, then any residual DOC in the water column can only "exit" via the main display overflow. Ie., if the skimmer doesn't fully extract all the "nasties" - the nasties then have to go through the sump, and then randomly through any frag tank and/or refugium back into the main display and back over the overflow for the skimmer to have any "second chances" to extract them. Maybe this is a gross oversimplication of skimmer theory and I'm wrong, but I wonder if this could be construed as a weakness in this idea... over just having the skimmer draw from the sump and return to the sump and recirculate that way.

[calkrog]

dale,

what we are trying to do though is restrict the flow from the display to get the herbie to be quiet. setup one you drew would work, with an additional valve so there is no free flow from the display. am i making sense?

[Dale]

If you mean trying to stop it from gurgling or gulping, the way to do it is to restrict the return pump flow with a valve post pump. I would never restrict the overflow rate myself.

[sphelps]

If possible you could also place a tee before the skimmer pump input, this way you could feed the overflow water directly into the skimmer pump rather than the skimmer body. If you did this you wouldn't have to worry about eliminating the overflow bubbles from the skimmer feed. It may even be beneficial to do the exact opposite as the previously posted schematics and send the highly aerated water to the skimmer while the lower aerated (quieter) water is sent into the sump.

I've has these pictures lying around from a previous project. Obviously not the same as your setup but I think the idea is the same.







HTH

[untamed]

If you placed only 1 gate valve on the exit of the skimmer, then the water levels in the skimmer and the overflow box would always match...requiring the skimmer to be exactly the right height. Two valves is the way to go. Then, you have indendent control over the water height in the skimmer and over the water height in the overflow box.

The limit, however, is that you will not be able to drive the water height in the skimmer HIGHER than the water height in the overflow box. If your skimmer is too tall, it won't work because you might not be able to get the water high enough in the skimmer body to make the skimmer function properly. So...you can make a skimmer too tall, but not too short.

That is the issue I'm having. I will require the skimmer to be shortened from spec in order for my gravity feed to work.

[Delphinus]

That's sort of what I was thinking too, untamed. My plan is just to build a table or shelf for the skimmer that will sit next to the overflow (since the back of the tank will be a tank room anyhow, it doesn't "need" to be under the stand). So the real trick will be finding the right height for the skimmer table, might need some trial and error.