Algae refugium vs. Scrubber ??

Vlado4x4

New member
I have an algae refugium with chaeto, gracilaria and ulva running for quite a long time, doing amazing. But would like to set up an algae scrubber to help me with my parameters.

Will the scrubber, once it matures enough, kill my algae refugium due to lack of nutrients ??
 
good to think about, i was planning on having a small scrubber on the water supply to my macro/rubble refuge on the new tank i am building. so i would like to hear more on this as well
 
Macro algae= you will need higher nutrients, mostly NO3, but they will take up more and are a bit more trouble to tend than ATS.

ATS: able to respond well to lower ppms of NO3 etc, but...........so can a NO3 bead reactor, so can a DBS etc.

ATS will remove PO4, but a well run macro tank can also, if fact, you might need to add a pulse here or there for the macros not to become too PO4 limited so they can maintain the NO3 uptake rate.

Both Refuge's and ATS's need some biomass export for removal, this also maintains the biomass to keep the removal rates of N and P relatively constant. You do not want feast or famine uptake rates, this leads to algae feast or famine in your main tanks.

Stable biomass= stable uptake rates.

ATS's are good for some critters as a source of food, while macros are preferred by others, this is a consideration also.

Macros look much prettier and can be sold, ATS? Not so much.
ATS's are better as utilitarian filters, and sunlight, windows etc can be used very well. ATS's also can provide good evapo transporation to cool the water down if you do the trickle over the vertical sheet method etc.

Something that might avoid a chiller for some aquariums.
Well engineered and thought out, the ATS offers a fair amount.

It's a more robust system, but a dense refuge looks good, has much nicer diversity and can do essentially all that you might need for a reef display. Yes, the ppm's/ppb's are tad higher to keep the macros going, but this translates into nicer coral and zooxanthellae. They will grow and use the ferts at low levels also. Depending on your feeding routine, the PO4 is the main control factor.

Some folks just feed more to prevent strong limitation of the macros by PO4, this in turn feeds the coral even better, and then the waste is removed rather quickly by the macros and the DBS in the refuge along with the fast growing macros takes care of the NO3.

Both systems can work well.

I think coral growth is likely better from what I've seen with the refuges that are managed to keep the relative same/similar biomass(eg, they prune once every 1 to 2 months etc).

Tang's gotta eat.
 
so you would recommend 1 or the other, not both? i would be much more inclined to go refugium only. i tend to feed A LOT anyways lol.
 
so you would recommend 1 or the other, not both? i would be much more inclined to go refugium only. i tend to feed A LOT anyways lol.

Depend on what you look for, if you want to lower no3 and po4 you should go towards the scrubber. If you want aesthetic porpuses and critter fabrication you'll want the algae refugium.

Right know i have both, but once the scrubber matures it will kill the refugium in the long run, due to lack of nutrients.
 
A refugium can certainly lower NO3 and PO4, very effectively in fact, the question how low do you want to go and how much work you want to put in it.

These are human factors.

I'm not so sure "less is better/best" when it comes to N and P, a stable low range is best IME/IMO.

That's the goal. Not absolution.
 
Depend on what you look for, if you want to lower no3 and po4 you should go towards the scrubber. If you want aesthetic porpuses and critter fabrication you'll want the algae refugium.

Right know i have both, but once the scrubber matures it will kill the refugium in the long run, due to lack of nutrients.

This can be avoided if you dose KNO3 or Ca(NO3) once/twice a week, about 3-5 ppm should be enough to prevent limitation.

Feed more to relieve any PO4 limitation.

Overdosing PO4 as KH2PO4= diatom bloom.
Occurs about 0.3-0.4 ppm IME.

But as long as the feeding is good, this should be too large a factor.
Macros will still grow, but not at a super fast rate.

If the NO3 bottoms out, then the macros will melt and go sexual.
This is mostly what burns people and causes the most myths with macro algae culture. They allow the biomass to keep building and growing and the supply of NO3 is less and less, their tank looks good about 1 months before the crash though.

I've seen this over 100X.

Adding a little NO3 is good.

Low NO3, not absent, same for PO4, but PO4 can be run down lower and can be more limiting without too much negative impact on macros or ATS.
 
i think for ease of maintenance and aesthetics, i will go with the refugium for now. the plumbing will be set up so that i can add the scrubber at any time if need be.
 
A strong scrubber, which uses the basics of strong light, flow, and attachment, will indeed kill off a fuge since the fuge appears as nuisance algae. Feeding more will stop this.

If the only consideration is size, the the scrubber can be about 1/20 the size, and 1/100 the weight, of a fuge. If the only consideration is growth of large pods (not just baby copepods), then a fuge is probably better, because each cleaning of a scrubber puts the pods population back to zero.

However the yet-to-be posted DIY designs for the floating surface scrubber may change this, since they allow harvesting without setting the pod population back to zero.
 
I think they are abut the same in effetiveness at N and P reduction . Different types of algae might outcompete one another . A refugium usually uses chaetomorpha or other selct macroagles not nuisance algae. I seriously doubt a scrubber at 1/20 the the size will do as well as a a fudge 20times larger.
 
I seriously doubt a scrubber at 1/20 the the size will do as well as a a fudge 20 times larger.

True.

The 3D structure in a fuge also helps and then there's the DBS aspect for N removal. Not much 3D structure on a turf scrubber. Vertical drip scrubbers are useful, particularly when you can operate them remotely against a window with natural sunlight.
 

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