Refugium with fish AND chaeto? Need ideas.

[dendro982]

Please, advice - I'm stuck:
1. Now I have the 5g bucket with chaeto and LR rubble as a refugium for keeping nitrates in check.
2. Also, I have to move the refugee scooter blenny in another tank (no two males in the same tank, even big). Now it's temporary in another room with tank, but water quality drops rapidly.

I thought about replacing the bucket with chaeto by 20g long tank, and using it as refugium with chaeto (or other macroalgae) for reducing nitrates AND for housing this scooter.

The problem rises - the scooter may tangle in the chaeto, or chaeto will float and mess the tank appearance.
May be place some divider - but it will reduce the light, available for algae, and reduce space for the fish. Horizontal divider - will make cleaning difficult.
Any other ideas? What did I miss, and is it viable idea at all - keeping them both?


The other macroalgae I have
(but don't know it's efficiency for reducing nitrates and how to make transition smooth from a large quantity of chaeto to the small quantity of the other macroalgae):

- grape caulerpa (yes, I know pitfalls here, plus it grows slower than chaeto in this conditions),
- blue bush algae Ochtodes - low light, grows fast (but I have at most 3 handfuls of it, and don't know anything about it, other than a nice appearance);

- red fern kelp - grows soooo slowly, may be for diversity only,
- the red sponge-like mass of algae, listed as gracillaria on some websites, but fish won't eat it, so could be red turf algae. Grows fast, but not so fast as blue algae.

- or make the white xenia refugium, or mix all - xenia, fish AND macroalgae?

Again, question how to make transition smooth from the large quantirty of chaeto to a small quantity of any of above, including xenia.

It will be bare bottom refugium, because of messy eaters in both tanks. Already tried sand (aragonite), tanks almost crashed, had to remove.

 

[piercho]

If you want a vegetative filter that is efficient, maximize the water flow rate and maximize the intensity of illumination. Rock is a bad addition, IME, as it takes up space, makes harvesting some algae more difficult, and makes siphoning out detritus more difficult. Rock is also a house for micrograzers that will consume algae and lower the net plant productivity of the filter. A sand/mud substrate filter along the lines of a Lyng Syn Ecosystems filter is more useful than rock/rubble, IMO, but I personally keep a bare veg filter to keep micrograzers at a minimum. IMO you should attempt to grow as many varieties of algae in the filter as you can keep going, but the most competitive alga for your current tank conditions will tend to dominate. A micrograzer predator like a scooter blenny might be a positive addition, IMO.

To an extent, you have to choose between competing goals when plumbling a "refugia" as a secondary tank. If you want the tank to be a net nutrient sink/export site, keep substrate and micrograzers to a minimum. If you want it to be a net microfauna producer, maximize substrate and eliminate predators. When the concept of highly efficient vegetative filters and microfauna refugia were proposed by Walter Adey going on 20 years ago, he kept the functions separate and in separate tanks. Combining them into one tank demands reducing the productivity of one or both of the goals.

If you are trying to implement a "BB" regimine - and I admit not fully understanding the goals of that husbandry - IMU there should not be any area of the system where detritus is allowed to accumulate or plants are encouraged to grow. Very high tank flow with a relatively high volume skimmer, UV and nothing else.

 

[dendro982]

Thank you for the input!
So, it's better to separate fucntions.
The possible problem with chaeto and the small fish - in physical safety of the fish - it could stuck/be tangled inside chaeto.
Anybody has info on comparative efficiency of these macroalgae?
How to make transition from big quantity of chaeto in the bucket to the smaller quantity of other algae in the 20L refugium smoother - by keeping them both bot some time and gradually reducing chaeto in the bucket?

The bare bottom idea - at least how I came to it, after aragonite sand bed in nanos - the people have inhabitants, that leave too much waste, that sand bed of this size can handle.

More like creating habitat for a particular type of animals, instead of stocking existing ecosystem by suitable habitants.

For me it's heavy feeding and removing leftovers in a few hours, before they start decompose. Quantity of food can't be reduced, only efficiently removed. And a really big system is not an option because of space and affordability.

 

[piercho]

Anybody has info on comparative efficiency of these macroalgae?

Nitrogen- versus phosphorus-limited growth
Dynamic Aquaria, Third Edition
My personal experience is that Chaetomorpha does well in what I subjectively call low-moderate nutrient conditions. It will not compete well and will eventually disappear in low nutrient conditions, and is subject to smothering by epiphytes in moderate-high nutrient conditions. Asparagopsis, Acanthophora, and Caulerpa racemosa/peltata will all out compete Chaeto in my tank, but all are potential pest algae. I have a variety of unidentified red turf algae currently growing in my algae filter, and these along with Acanthophora comprise most of my export from the filter. In the tank I occasionally harvest Caulerpa peltata, a Halimeda species, and shoal grass. Both my tank and filter are lit by daylight metal halide lamps.

 

[dendro982]

Thank you!
In my low light systems, the feathery caulerpa (C. taxilifolia?) was outcompeted by chaeto and, in much lesser degree, by grape caulerpa.