Detritus as fertilizer

[121]

Would small amounts of skimmate and detritus make a good food source for phytoplankton and brine shrimp cultures?

 

[disc1]

You wouldn't have any control over what's in it or at what level. I wouldn't.

 

[121]

That's the thing. Wild phytoplankton relies on sunlight and upwelling for nutrient, which is detritus.

 

[disc1]

That's the thing. Wild phytoplankton relies on sunlight and upwelling for nutrient, which is detritus.

In the ocean you're right. But in the tank we have neither the volume or biodiversity. Consequently, we don't have very diverse poo. What wells up in the ocean, and what is sitting on the bottom of your tank may be very different. Things almost always work differently in small closed systems.

 

[lordofthereef]

All that said, why not try it and see? On a small phyto batch, of course. Worse thing that can happen is it fails, and you get to dump a small batch, right?

 

[121]

Disc1,

I'm assuming phyto doesn't need a biologically diverse poo, as long as it contains the basic building blocks like nitrogen and phosphate, maybe carbon?

lordofthereef,

I was thinking that maybe I'll be replenishing some trace elements back to the tank this way. Obviously a water change is better. I'm sure we lose a lot of trace elements from metabolic waste in the detritus. Why add an additional fertilizer and increase nitrates and PO4 when you can recycle what was already present?

 

[Paul B]

No, but brewers yeast is a good food source for that.

 

[121]

What about a phytoplankton reactor, plumbed into the sump with a slow water feed back to the main display? Could the reactor feed off of the waste and not crash if dialed correctly?

 

[disc1]

Oh I'm sure it could. I didn't realize you were experimenting. I thought you were talking about dumping crap out of your tank into an existing phyto system. Hell yeah, try it on a batch. I'm betting you'll have a hard time maintaining sterility, but if you're not worried about that you're all go.

 

[disc1]

Oh, that's the other difference. Bigger one I guess. In the ocean, all kinds of phyto are there at a low concentration. You would need a large culture, on the order of ocean sized, to feed like that. In the culture, you want one species of phyto at a time. And you want to grow them to a ridiculous concentration, green water. You will need a concentration of nutrients way above what is in the ocean. You might or might not get that from detritus from your tank.

What will definitely come with detritus is other living stuff. Mostly bacteria. They will compete for nutrients in your phyto culture. They may or may not crash the culture, but you won't get an optimal culture.

 

[121]

Disk1,

I might try experimenting with the phyto reactor idea. I forgot to mention that I have no fish and occasionally only target feed my corals. Because of this I don't skim. I'd like to add a pair of mandarins, so a constant phyto feed would be great to boost my copepod population.

Oh, that's the other difference. Bigger one I guess. In the ocean, all kinds of phyto are there at a low concentration.

Yes, but phyto only lives on the surface were it can get light. It feeds zooplankton and starts the food chain. This explains why pelagic fry are attracted to light.

You would need a large culture, on the order of ocean sized, to feed like that.

Maybe not. If the return feed is dialed correctly.

In the culture, you want one species of phyto at a time. And you want to grow them to a ridiculous concentration, green water.

I'm ordering some Teraselmis tomorrow to start me off. I think I'll avoid a dense concentration to prevent a crash, but this will depend on how I've dialed the reactor experiment.

You will need a concentration of nutrients way above what is in the ocean. You might or might not get that from detritus from your tank.

I'm assuming the natural reef has less free nutrients than most reef aquariums, due to all of the micro organisms competing for N and P. We obviously don't have that diversity so the DOCs might be available.

What will definitely come with detritus is other living stuff. Mostly bacteria. They will compete for nutrients in your phyto culture. They may or may not crash the culture, but you won't get an optimal culture.

I agree, but aren't those bacterias also present in the reefs? If I try the reactor I would like to dial it to last for maybe a month at a time before starting a new culture. I'm just throwing out ideas though. Thanks for the feedback.

 

[disc1]

Yes, those bacteria are on the reef, but the reef is WAY different than your culture. Think of it this way, ich and gill flukes also live on the reef, but we try to get them out of the tank right? It's the same with cyanobacteria and a phyto culture. There are big differences between the two ecosystems of an open reef and a closed culture.

Still no reason not to do the experiment. I have seen one phyto-fuge tried before.