Converting refugium DSB to seagrasses

[jusdave]

I have a 55g tank plumbed into my sump that also serves my 180g tank, and serves as a refugium / RDSB (4-6"). I started out with various caulerpa species, as well as cheato and a few shoots of turtle grass.

After experiencing one full blown 'sexual' event from my c. taxafolia, and two imminent ones from c. prolifera, I've removed most of the caulerpa species.

As the NNR and nitrate export kicked in, the cheato outcompeted most of the caulerpas. (I now harvest a larger than softball sized chunk a week.)

The only problem that I really have is that this is a display refugium that I'd like to appreciate more. The cheato has a tendency to get in and around what little caulerpa I have left, as well as the turtle grass and the LR rubble I've piled in a corner of the tank.

That's the setup, so here's the question. I'd like to convert this to a true sea grass bed, with a separate 29g tank just for cheato. Having read Sarah's wonderful article, I realized that my 4-6" DSB may not be the best substrate for turtle grass.

How would you convert it? Move the DSB to the new chaeto tank and start with mud in the 55? Or leave the DSB and put a layer of mud on top of it, with another layer of sand on top of that? Some other configuration?

 

[graveyardworm]

I realized that my 4-6" DSB may not be the best substrate for turtle grass.

What kind of substrate do you have?

 

[jusdave]

Pavestone brand crushed limestone (aragonite sand substitute) with a couple of inches of caribsea live sand.

 

[graveyardworm]

Is the particle size of the limestone fine, or course?

 

[jusdave]

It's quite fine. Can't get southdown here, so this is a good substitute.

 

[graveyardworm]

It sounds as though the substrate you have is fine, 4 inches is alittle shallow for a species like Thalassia, but you can build up the depth slowly like a 1/4 inch every couple weeks. The most important thing is that the sandbed is aged. Seagrass are capable of growing in many different substrates.

Can you pull the quote from Sarahs article that leads you to believe your substrate isnt appropriate.

 

[jusdave]

Wild collected mud from salt marshes, estuaries, lagoons or bays that already support seagrasses can be used after large debris and potential pests such as unwanted snails, worms, and ghost shrimp are manually removed. Commercially available refugium mud supplements can also be used in place of, or in addition to, wild substrate. The mud should be mixed with aragonite or silica sand into a loamy media and laid down as the first one to two inch layer of the bed, and then capped with clean aragonite, silica or calcite sand to an appropriate depth.

I'll be going to the Texas coast in a couple of weeks to collect peppermint shrimp, so I may get a bucket of good thick mud, if it's really necessary for the grasses. I'm just curious if it needs to be the absolute bottom, or if I can mix it in with the existing substrate.

 

[graveyardworm]

I think the main reason for putting at the bottom is to reduce silt storms in the tank. I prefer a white look to the sand so personally I would want it at the bottom.

I dont believe its totaly necessary for the seagrass to have mud other than as Sarah suggests natural microbial population aid in the survival of transplanted Thalassia, but for it to be a benefit I believe it would need to be collected from a seagrass bed containg Thallasia, but on the other hand I dont think it would hurt.

If you do go that route I would save the existing substrate and put it back in on top of the mud. Then give it time to settle, cycle, mature, and basically reestablish itself.

My only question would be how long does the mud remain viable as a benefit to the seagrass, and should I eventually change it out? Is it going to be worth it as a long term addition to the tank? Short term it probably has many benefits.

 

[jusdave]

Good point.. if it serves primarily as a source of minerals (iron, specifically) I'd think at some point it would be exhausted due to agressive skimming.

 

[Avast Marine]

Sure, but if you get it free (plus the cost of gas) it may be a easily renewable source of mineral content. I would think you would get a silt storm if removing a portion and adding some more, but the benefit could outweight the inconvenience. Just a thought.

 

[graveyardworm]

If I had access to mud from a tropical climate I would probably do it. The only mud I can collect up here in NH is temperate so I'm a little leary about using it, but I may try just the same.

 

[jeremai]

Just a question: if you are converting to a true seagrass bed, why skim or plumb in a chaeto tank? It seems a bit redundant to me; the seagrass should do both jobs more than adequately.

 

[jusdave]

<a href=showthread.php?s=&postid=7682214#post7682214 target=_blank>Originally posted</a> by jeremai
Just a question: if you are converting to a true seagrass bed, why skim or plumb in a chaeto tank? It seems a bit redundant to me; the seagrass should do both jobs more than adequately.

I'm assuming that If I plant a large field of grasses, there's going to be some time before the grasses take over nitrate uptake at the rate my chaeto is growing. The refugium pump draws from and dumps back into my sump after the skimmer, but of course some of it is going to get to the skimmer.

The reason it's plumbed inline with my other tanks is to take advantage of the larger volume of water- namely stability. Right now the total volume of my system is ~260g. I have an ATO and Kalkwasser drip that keeps the parameters spot on, unlike my 29g qt that I really have to work at to keep stable.

 

[jusdave]

Additionally, I understand that true sea grasses don't take in nutrients from the water column, but from the substrate. If I pulled the chaeto, I'm assuming there'd be some time before the nitrates filtered down into the substrate, if at all.

 

[graveyardworm]

Additionally, I understand that true sea grasses don't take in nutrients from the water column, but from the substrate.

I'm pretty sure that seagrass can uptake nutrients from both substrate and water column. I'll try to provide the reference tonight when I have a little more time to find it.

 

[Samala]

I think its very reasonable to keep the Chaeto online until the grasses are capable of filtering the system on their own. The amount of skimmate that is produced should steadily drop as well as the grasses grow.

Seagrass can pull nutrients from both the water column and the substrate.

>Sarah

 

[graveyardworm]

Are seagrasses better suited to pulling nutrients from the substrate or water, or does it no make a difference as long as its available.

 

[jusdave]

<a href=showthread.php?s=&postid=7684077#post7684077 target=_blank>Originally posted</a> by Samala
I think its very reasonable to keep the Chaeto online until the grasses are capable of filtering the system on their own. The amount of skimmate that is produced should steadily drop as well as the grasses grow.

Seagrass can pull nutrients from both the water column and the substrate.

>Sarah

Thanks, Sarah. With an established DSB, would you recommend I harvest some mud and incorporate it into the substrate or just increase the depth of the bed to one that's appropriate for turtle grass?