Does phyto not also live in the refugium?

[eggyplantz]

Apologies if this is a silly question but I'm not finding exactly the info I'm after.

My understanding is that a refugium established with macroalgae and whatever else acts as a place for copepods to reproduce safely and sustainably. But what is stopping phytoplankton from also reproducing in there? If one has a "full" refugium (strong light on reverse timer, substrate, live rock, thriving macros) is phyto supplementation still necessary or does it hit a point where they become self sustaining like the copepods?

Edit to add: Assume no mechanical filtration or skimming either, just biological and refugium.

 

[KrisReef]

Planktonic life tends to move with the tank water and doesn’t stay in the refugium where the lights are on

 

[eggyplantz]

Planktonic life tends to move with the tank water and doesn’t stay in the refugium where the lights are on

I'm assuming this answer was in good faith and not sarcastic so I'll ask: is this not what the reverse light cycle accomplishes? So that some part of the system's water is being lit at all times?

 

[KrisReef]

I'm assuming this answer was in good faith and not sarcastic so I'll ask: is this not what the reverse light cycle accomplishes? So that some part of the system's water is being lit at all times?

That is done to stabilize oxygenation (by photosynthesis) and to stabilize pH.

 

[eggyplantz]

That is done to stabilize oxygenation (by photosynthesis) and to stabilize pH.

I'm aware of the primary purpose of the reverse light cycle. Since the implication of your extremely brief response was that phyto is light dependant, my question was if that would ALSO help with phyto reproduction.

 

[Garf]

I'm aware of the primary purpose of the reverse light cycle. Since the implication of your extremely brief response was that phyto is light dependant, my question was if that would ALSO help with phyto reproduction.

The phyto normally cultured for reefs are very sensitive to contaminants as far as I can tell. I’ve tried a few times to grow it in tank water, failed, gave up. I made the assumption bacteria feasted upon it, but could have been something else. That said, Refugiums will grow single cell algae, just as single cell algae will grow on glass in the display. It’s very rare that we see a tank taken over by a phyto bloom, it’s normally bacterial, another assumption.

 

[eggyplantz]

The phyto normally cultured for reefs are very sensitive to contaminants as far as I can tell. I’ve tried a few times to grow it in tank water, failed, gave up. I made the assumption bacteria feasted upon it, but could have been something else. That said, Refugiums will grow single cell algae, just as single cell algae will grow on glass in the display. It’s very rare that we see a tank taken over by a phyto bloom, it’s normally bacterial, another assumption.

Interesting, I guess this would explain why phyto cultivation kits all talk about sterilizing so much.

Out of curiosity how did you know you failed with tank water? Is there a way to test for their presence or did you attempt to use tank water in a separate culture vs fresh new saltwater or something?

 

[Garf]

Interesting, I guess this would explain why phyto cultivation kits all talk about sterilizing so much.

Out of curiosity how did you know you failed with tank water? Is there a way to test for their presence or did you attempt to use tank water in a separate culture vs fresh new saltwater or something?

Yes, it was tank water in a seperate container. Some folk bleach old water I believe, before they try and grow stuff, after dechlorination procedures. I didn’t know about that, when I tried it, lol.

 

[afboundguy]

I would hazard a guess that you could in theory grow it in a refugium if there as not flow and it was contained within the refugium but I would think that would negate the benefits of a refugium.

I am by no means an expert but I have been dosing my tank with phyto for some time and the tank just uses it up too quickly for it to grow in the tank. Even before I setup up a dosing pump and I would manually add a lot causing my DT to get cloudy it wouldn't last that long.

I used to use NSW since I live on the coast and I know there was tons of phyto in that water but I couldn't really see it with the naked eye. If you constantly dose phyto it's in the tank but just gets eaten before it can duplicate unlike in the ocean where there's way more areas of wide open ocean for phytoplankton to grow.

 

[eggyplantz]

Yes, it was tank water in a seperate container. Some folk bleach old water I believe, before they try and grow stuff, after dechlorination procedures. I didn’t know about that, when I tried it, lol.

Good to know. I've been looking at a cultivation setup from Poseidon for phyto and in all the forum threads and various things I've read don't really answer why it doesn't exist naturally in the reef system along with everything else, so I was curious. It seems like the pieces should all be there but maybe the sheer level of predation from everything including bacteria is just too high.

 

[eggyplantz]

I would hazard a guess that you could in theory grow it in a refugium if there as not flow and it was contained within the refugium but I would think that would negate the benefits of a refugium.

I am by no means an expert but I have been dosing my tank with phyto for some time and the tank just uses it up too quickly for it to grow in the tank. Even before I setup up a dosing pump and I would manually add a lot causing my DT to get cloudy it wouldn't last that long.

I used to use NSW since I live on the coast and I know there was tons of phyto in that water but I couldn't really see it with the naked eye. If you constantly dose phyto it's in the tank but just gets eaten before it can duplicate unlike in the ocean where there's way more areas of wide open ocean for phytoplankton to grow.

Appreciate this, thanks. Seems down to quantity in vs out, so better thought of as a temporary food source than a self sustaining living organism in its own right once in the tank.

 

[dansyr]

Appreciate this, thanks. Seems down to quantity in vs out, so better thought of as a temporary food source than a self sustaining living organism in its own right once in the tank.

Practically, yes a temporary food source. If you're interested in the 'why', a couple reasons why the end up different than other microscopic critters you add in -

1) typically-added phytoplankton are usually always planktonic (in the water column), vs copepods that may be planktonic but also may hop along surfaces. Look up 'boundary layer flow' for why this matters - if you are motile and tiny but hang out near surfaces, you can avoid flow despite being plankton-sized. So it's 'easy' for certain pods to stay in a refugium and only some portion of them wash out into water column, but phyto that stay fully planktonic (in the water column) don't have that advantage.

2) turnover time - related to #1, if there is any current flowing from refugium, and they aren't motile enough to intentionally utilize the boundary layer, there is nothing keeping them there. So the only way to keep a standing population in a refugium is to have the turnover so slow that they can divide while they're in there (basically a bioreactor). But the issue is that fast-growing phytoplankton might double every 12h or slightly slower, so your turnover rate would need to be 0.08x. but i don't know anyone running a refugium with flow that low.

3) phytoplankton growth requirements - most phytoplankton we grow aren't actually found on reefs. Broadly speaking, commercially cultured types like Thalassiosira, chaetoceros, are often found in relatively nutrient-rich waters (why they like being cultured) like subtropical coasts, or estuaries. Coral reefs have muuuuuch lower nutrients, and so the types of phyto that occur there are much slower growing with finickier growth conditions (broadly speaking). So putting high-nutrient, cooler-water preferring species into low-nutrient, tropical waters really puts them at a disadvantage. Plus all the points about contamination Garf mentioned, but also there are microbes, pods, inverts, and corals that all want to eat them.

 

[eggyplantz]

Practically, yes a temporary food source. If you're interested in the 'why', a couple reasons why the end up different than other microscopic critters you add in -

1) typically-added phytoplankton are usually always planktonic (in the water column), vs copepods that may be planktonic but also may hop along surfaces. Look up 'boundary layer flow' for why this matters - if you are motile and tiny but hang out near surfaces, you can avoid flow despite being plankton-sized. So it's 'easy' for certain pods to stay in a refugium and only some portion of them wash out into water column, but phyto that stay fully planktonic (in the water column) don't have that advantage.

2) turnover time - related to #1, if there is any current flowing from refugium, and they aren't motile enough to intentionally utilize the boundary layer, there is nothing keeping them there. So the only way to keep a standing population in a refugium is to have the turnover so slow that they can divide while they're in there (basically a bioreactor). But the issue is that fast-growing phytoplankton might double every 12h or slightly slower, so your turnover rate would need to be 0.08x. but i don't know anyone running a refugium with flow that low.

3) phytoplankton growth requirements - most phytoplankton we grow aren't actually found on reefs. Broadly speaking, commercially cultured types like Thalassiosira, chaetoceros, are often found in relatively nutrient-rich waters (why they like being cultured) like subtropical coasts, or estuaries. Coral reefs have muuuuuch lower nutrients, and so the types of phyto that occur there are much slower growing with finickier growth conditions (broadly speaking). So putting high-nutrient, cooler-water preferring species into low-nutrient, tropical waters really puts them at a disadvantage. Plus all the points about contamination Garf mentioned, but also there are microbes, pods, inverts, and corals that all want to eat them.

This is exactly the kind of answer I was interested in, thank you so much for breaking it down clearly and in detail.

Time to get some cultures started!