Converting 29g FOWLR to macroalgae?

[Betta132]

I currently have a 29 biocube saltwater tank. Stock:
4 large-ish aptasia (surprisingly not spreading, plan to kill soon)
About two dozen small unknown polyps (zooanthids, maybe)
One yellowtail blue damsel (flares at things, darts away if it even twitches back, though, not aggressive, just sort of puffy)
One rooster waspfish (max size under 3", carnivorous and somewhat venomous but very gentle, although it doesn't particularly like the goby)
One Wheeler's shrimpgoby (about 1 1/4" currently, peaceful, retreats into tunnel when the wasp goes after it but doesn't seem bothered at all)
One 3" tiger pistol shrimp (seen it shoot at the waspfish a few times, never hurt the wasp, not aggressive but may have eaten my bristleworms)

I'd like to convert this to a macroalgae tank for several reasons;
They're unusual
They look neat
They're supposed to be fairly low-maintenance if you get the right species
Fish should like it
Waspfish is shy now, but is a macroalgae-living species in the wild and might get bolder if there's stuff for it to sit in
Should increase numbers of microorganisms in there

Here's what I'd like;
Macroalgae that doesn't take much increased maintenance
Something red for the waspy to sit in, hoping he'll come out more if he has a plant spot - maybe that dragon's tongue stuff?
A decent amount of macroalgae to make it look sort of like a planted tank
Maybe some seagrass? Is there something that'll be happy growing in regular sand?
Something that looks like a freshwater plant. Maybe that feather-looking stuff I've seen? Something that'll sprout leaves and stems would be nice.
Something that'll help outcompete the algae on the walls, which I'm guessing is everything.

I've been doing some research, but it looks like macroalgae tanks being uncommon means that no one really has any advice for making what amounts to a marine planted tank.
I've read that if you keep enough macroalgae species, they all outcompete eachother and nothing can go insane and take over. True? Because that sounds cool...
Sargassum shrimp. I know where to get a lot of assorted ones of these... Would they enjoy a macroalgae tank, do you think? They live in clumps of floating sargassum in the wild, but they don't need it to survive, they're basically just little shrimp that attempt to pretend they're bits of sargassm.

 

[Betta132]

Bump...

 

[madeyemary]

I have not kept sargassum but know it requires a ton of light due to floating near the top of the water in its natural environment. Something like 5w/gallon if I'm not mistaken. Certainly not an easy macro.

 

[tektite]

Sounds like you'll want caulerpa. Easy to grow (in fact most are quite invasive) but can grow in sand or over rock, sends out runners and 'leaves'. Just read up on its downsides like going sexual and make preparations to prevent and handle it if it occurs. No seagrass, very difficult, require specialized care, substrate, and high light. Easy reds like Halymenia (dragon's tongue) and Gracilaria are good starters. Halymenia won't attach to the rockwork on its own though. Some Gracilaria does, red titan will also grow onto the rock and stay in place, plus is hardy.

Keeping a lot of different species - what you heard is absolutely wrong. Macroalgae tanks are like gardens. Different species grow at different rates, some are hardier than others. Without judicious pruning and care, over time especially with invasive fast growers like caulerpa, one or more macros will outcompete others for space, nutrients, and light.

A lot of macro tanks look great in the first few months, but its over time that they become surprisingly hard. Just look at the number of macroalgae tank threads posted in this forum. Lots of cool pics from the beginning, then pics of decreasing beauty or silence after some time. Macros outcompeting each other, dying off with no real reason, nuisance macroalgae like hair algae taking over...given that more delicate macros need good conditions to grow in - the right light, balanced amount of nutrients - that usually means the tank is awesome for hardier nuisance algae! Finding a balance of nutrients, physical macros, pruning schedules, etc over time can be a hard thing to figure out.

No problem with sargassum shrimp, I've had some in my macro tank in the past. They just hide a lot so you really don't see them much.

Experience level - been keeping macros and macroalgae tanks for 5+ years now.

 

[Betta132]

Alright, thank you.
What I'm hoping for is kind of a tangle of plants in the back, mostly greens with a few bits of red, and a more or less open space in the front for my damselfish. Is that doable? I don't mind going in and yanking out hunks of plant now and then.
I'd like to keep it to just a few of the hardier species, so should I just go for dragon's tongue, Gracilaria, and a slower-ish caulerpa?
Is there a caulerpa species that's slower growing and therefore less likely to suck up all the nutrients and go sexual? If I remember correctly, it does that when it's out of nutrients and is therefore trying to spread before it dies..

 

[tektite]

Caulerpa prolifera would be the one I recommend. Not terribly fast growing and is not bad as far as going sexual. There can be many triggers for that. The best way to prevent it is to cut the runner of the caulerpa into pieces as it grows. When it goes sexual the whole section goes. If the caulerpa is just allowed to grow as one giant interconnected piece, if it goes sexual it ALL goes. If the runner is cut, keeping it in several pieces, usually only one piece will go. Both keeps some caulerpa in the tank still living, and lessens the impact of the released spores on the tank inhabitants.

 

[Betta132]

Okay, thanks! I have a pair of stainless-steel scissors, and I'm pretty sure those are considered aquarium-safe, so I can do that.
By any chance, do you or your buzzy little mandarin friend know a good source for those three aquatic plants?

 

[tektite]

My favorite place for macroalgae online is gulf coast ecosystems. Good prices and very generous portions. Very well packaged. However...this time of year is the worst for buying macroalgae, as the few places that do sell them mostly collect them seasonally. Other than that, forum classifieds can sometimes net you the more rarer and unique varieties, from all over not just the Gulf of Mexico.

 

[Betta132]

Alright, thank you. When is a good season for collecting macroalgae? Spring? Summer?

 

[tektite]

Late spring through fall.

 

[Betta132]

I just read that the best way to kill excess caulerpa for disposal is to microwave it for a minute or two. True? I mean, I'm pretty sure that'd kill just about everything... What about caulerpa?
I know extra precautions would be good if disposing of water full of caulerpa spores, but I'm assuming that so long as it hasn't gone sexual the water doesn't need any special treatment.