Trying something new - Walstad method and NPS filter feeder tank

brittlestar · Jan 26, 2026

It looks like after about two weeks the system is cycled. I haven't been watching the nutrient levels closely but I just tested today and it's all pretty low. The bacteria and microfauna must be doing a good job of processing/uptaking all the organic matter, and the soil isn't causing any problems. I've been adding plenty of fish food too. The caulerpa is growing and spaghetti worms have become visible in the sand. I'm gonna give it a bit more time just to be safe and then add my feather duster.

brittlestar · Jan 29, 2026

Here's what the substrate looks like so far. Lots of bubbles near the top, a couple dark blotches in the sand, and a band of diatoms right above the soil. I have a feeling this is gonna get very colorful.

brittlestar · Jan 29, 2026

Also I did a water change and added the feather duster, elegance coral, and dosing pump. The elegance isn't very happy about being moved but the duster is fine.

brittlestar · Jan 29, 2026

And I got a couple of those little hitchhiker feather dusters that like to grow in the sand from the LFS

brittlestar · Feb 1, 2026

The bottom of the tank is totally orange. Anyone know what that is?

brittlestar · Mar 20, 2026

It's been about a month and a half since the last update and it's all working beautifully so far. The three Caulerpa species are all thriving - the C. lentillifera in particular is growing explosively, with more pale new growth than mature fronds. The mangrove has put out a new pair of leaves and it's working on another. The Gracilaria hayi is growing but it doesn't seem to like the bright light and is staying a pale yellowy orange except where it's shaded by Caulerpa. I haven't trimmed anything so it's blending together into one big beautiful green mass. Except for a brief diatom phase at the start, I haven't had any real issues with microalgaes, but the glass does get pretty cloudy if I don't clean it off at least twice a week. I don't mind since I can just look in from above. As I was hoping, the pod population is massive. The glass is just covered in little creatures grazing on diatoms and gravid copepods are abundant in the water. Amphipods are crawling on every surface too. The substrate is slowly filling with burrows as the various worms establish populations. Starting about half an inch below the surface, there's a rainbow of different bacterial colonies all mixed together in a continually shifting patchwork. As far as I can tell, the Walstad method does work just as well in saltwater... for at least a couple months :P

The only problem I've encountered is that I really can't slip up with these filter feeders, not even the "easy" feather dusters. If I miss a water change, or I don't feed them for a day or two, they immediately suffer. At one point I ran out of phyto feast for a couple weeks and thought I could get away with just feeding them spirulina powder until I could get more. The largest one, despite being healthy until then, dropped its crown in that time. It has since grown a new one, which is about two thirds the size, and seems to be regaining its strength as long as I am extremely consistent with food and water changes. One of the small hitchhiker feather dusters also disappeared. Presumably it's somewhere else in the tank. I was worried that might happen, since the guy at the fish store was pretty rough with the tube (I don't blame him, it's the width of a pencil lead and made of sand...)

One more thing - I read that C. lentillifera is edible and a popular food in its native range, and at this point I have more than enough, so I decided to try some. Have you ever tasted something that was so overwhelmingly sweet you couldn't bear to swallow it? It was a bit like that, but instead of sweet, it was umami. I love seaweed, but I've never eaten something so strongly seaweed flavored in my life. It might be good as an addition to something else.