Can I Put Chaeto in My Display Tank?

The prolific green algae Chaetomorpha spp. has become
one of the most widely used “macros” by saltwater aquarists. Generally, it is
maintained in large clumps within a specially set up refugium. In some other
cases, it is kept in so-called algae reactors (indeed, Chaetomorpha is
by far the most commonly used algae for this). However, once in a while, a
hobbyist inquires as to whether or not it is possible to cultivate these algae
inside the main tank alongside corals, clams, etc.

The short answer is, yes. Of course you can put it in
there. The better question, however, is “do you really want to?” And “if so,
why?”

Back “in the day,” a lot of hobbyists similarly experimented
with Caulerpa spp. Explaining that they liked the “greenery” and just
wanted to have a little bit for variety, they’d throw a small wad somewhere on
the bottom of the display. Problem was, that fast grower almost always won
pruning races against the keeper, with the result being corals and other
sessile inverts getting overgrown and irritated--seemingly overnight.

So, maybe “chaeto” isn’t quite as invasive as Caulerpa.
But the same sort of thing can occur. Chaeto is messy and can grow quite
rapidly under the “right” conditions. Just saying...

If you really, really like pruning and picking at your tank,
then by all means, add some chaeto to the display. But we could only suggest
such a thing--all the above cautions thoroughly emphasized--if you intend to
maintain small, ornamental patches of the stuff. And, we’d also suggest some of
the much slower-growing, less invasive, varieties such as dragon’s tongue Halymenia or blue Hypnea instead.

If you intend to keep enough chaeto in your system to
reliably maintain low dissolved nutrient levels, then we must suggest that you
grow it in a refugium or reactor only!