Will flow rate effect Refugium performance?

[budster.stig1]

I have a 70g "Duplex Refugium" that is currently processing about 1200gph from two sources 1) Skimmer effluent 2) main return supply. My system is 325g total capacity running about 1800gph total circulation. My question is this, Will flow rate through the fuge effect it's ability to assimilate po3. I have a good crop of Culerpa which I harvest about once a month, it seems to thrive OK, but I cannot reduce the po3 below 10-15 ppm. If I divert about 1/2 of that flow, will the slower exchange of water through the fuge give it more time to assimilate more po3? A little input on this subject from anyone with knowledge in this area would be appreciated. Thanks.............Budster

[hobbzz]

Slow flow through the fuge is what you want. Generally 2-5 times display volume. If you are doing macro only, then you would want higher circulation within the fuge to the keep the caulerpa tumbling. So about 600gph through the fuge, then higher circulation using powerheads. Amthony calfo did the research and came to this conclusion over a decade ago but it's suprisingly not widely known. You want it tumbling to allow the light to hit all sides of the macro growth, but slow flow through it to allow greater contact time.

[budster.stig1]

Originally Posted by hobbzz

Slow flow through the fuge is what you want. Generally 2-5 times display volume. If you are doing macro only, then you would want higher circulation within the fuge to the keep the caulerpa tumbling. So about 600gph through the fuge, then higher circulation using powerheads. Amthony calfo did the research and came to this conclusion over a decade ago but it's suprisingly not widely known. You want it tumbling to allow the light to hit all sides of the macro growth.

Thanks for info., My display is 210g, total system with sumps, refugium and frag tank is 325g. The top of the fuge (upper 1/2) is a tray of rubble with the macro above, the bottom 1/2 is a structured benthic zone. Most of the flow is directed across the top 1/2 of the fuge. using a rate 2 to 5 times the DT, I will need to target about 400gph to 1000gph across the macro. I can easily divert 600gph to the return sump from the skimmer, leaving 600gph through the fuge. I guess the only way to determine the result is to try it out. I really need to reduce po3 to accelerate frag tank success.

[davocean]

If you are harvesting that much macro then I would say your flow is fine.
That big of a system I'm sure there would be room to add biopellet or phos reactors or even both.
I don't count on my fuge for removing everything, and reactors would be much more efficient in doing so.
I look at my fuge for pods, any nutrient export is just a bonus.

[hobbzz]

You could also dose vinegar or vodka.

[budster.stig1]

Originally Posted by davocean

If you are harvesting that much macro then I would say your flow is fine.
That big of a system I'm sure there would be room to add biopellet or phos reactors or even both.
I don't count on my fuge for removing everything, and reactors would be much more efficient in doing so.
I look at my fuge for pods, any nutrient export is just a bonus.

I agree that the nutrient removal is good, but could it be better with slower flow? My #1 focus in this project is to accomplish my goal using as little energy possible and utilizing natural processes whenever possible. I appreciate your input, I would just like to avoid the reactors to the extent possible. I use GFO in a filter sock stuck in my sump for po4 control, my po4 is steady at .02. If I could avoid a denitrator through more efficient macro algae management it would be great

[budster.stig1]

Originally Posted by hobbzz

You could also dose vinegar or vodka.

Have considered it, not sure I have effective dosing amounts and dosing info. I try to avoid any daily dosing, however if a dosing pump and set-up are required then I could do that, just not sold on the effectiveness of dosing Vodka, would like to try improved Macro algae management first...

[davocean]

Yeah, if you don't have a full understanding of dosing vodka it's not something to wing, and I don't for that and other reasons.
You could run two reactors inline off one small pump and it would do much more for you than just the fuge.
FWIW I run at 5x turnover, and my macro grew slow, and actually grew faster when I had an additional pump placed in there, so while I agree w/ a low flow sump/fuge, at about that 5x turnover rate for the skimmer and other reasons, having a little more flow should not harm and could possibly even benefit, to a point.
I suppose if you could T something off and play w/ it to find that sweet spot, but honestly sounds like you are getting all you can out of it already, or darn close to it anyway.

[budster.stig1]

Originally Posted by davocean

Yeah, if you don't have a full understanding of dosing vodka it's not something to wing, and I don't for that and other reasons.
You could run two reactors inline off one small pump and it would do much more for you than just the fuge.
FWIW I run at 5x turnover, and my macro grew slow, and actually grew faster when I had an additional pump placed in there, so while I agree w/ a low flow sump/fuge, at about that 5x turnover rate for the skimmer and other reasons, having a little more flow should not harm and could possibly even benefit, to a point.
I suppose if you could T something off and play w/ it to find that sweet spot, but honestly sounds like you are getting all you can out of it already, or darn close to it anyway.

Davocean: Thanks for comments, I guess I will experiment a little.

Budster

[davocean]

You could also try to reduce what is going in, rinse mysis in your DI water, many do that, lighten feedings, and a good thing to do is feed w/ a turkey baster so you can aim at feeding fish, and not the tank.

[budster.stig1]

Where's the experts? Any one else have experience with this issue?

[davocean]

Originally Posted by budster.stig1

Where's the experts? Any one else have experience with this issue?

Hmmff, I'm only 29 years into this hobby, hopefully at 30 someone might consider me an expert!

[budster.stig1]

Originally Posted by davocean

Hmmff, I'm only 29 years into this hobby, hopefully at 30 someone might consider me an expert!

Sorry, no insult intended!

[davocean]

All good, I joke a lot, but in all honesty I doubt anyone that has been around will say much different.
A fuge is for pods, nutrient export is just a side benefit, and we have much better tools available to deal w/ nutrient issues, and if pulling it out via reactor is not a viable option, then you need to do what you can to put less in, and possibly step up on quality WC's.