Seagrass or Deep Reef?

[KingOfAll_Tyrants]

So I had a tank disaster a few weeks ago, and am plotting getting back in, maybe as soon as in the next two weeks.

 

I want to go low-ambition this time, because a) I want something a bit easier than the sort of ad hoc, no plan SPS system I had b) this summer, once the virus stuff dies down, we want to do a lot of remodeling in the area and a smaller initial tank would make that easier.  (though I'm aware that what is temporarily expedient becomes much more permanent than anyone desires).   

 

Anyway, given all that, I want to restart with a 20 gallon tank vice the 40B I initially was going to start with (my ambition is 2-3 40Bs reflecting a seagrass lagoon, an acro-heavy upper reef, and then a lower/mesophotic reef, but that's for later - who knows when?).   

 

So, I have two ideas:

 

1. seagrass lagoon.    Part shallow sandbed with in-sand macroalgae to quickly outcompete algae, part deep sandbed with lots of nutrients in the sandbed for the cultivation of easy seagrasses like halophila, as well as deep-sandbed loving macros like Halimeda incrassata.   This would be to some degree a saltwater planted tank.  I will slowly add a modest number of fish.  I would have to regularly dose carbon (via a planted tank CO2 system), NO3, and even phosphates, maybe even iron or somesuch.  I would need to have a constant pH and carbon/oxygen monitor (either seneye or apex.  Leaning toward the former because even though I have an apex brain the pH and ORP probes are almost as expensive, though wifi support seems to be better with the apex)

 

My worries about this are a) the sandbed b) the lack of abundant turn-key type instructions for seagrass tanks c) the fact that to keep this in check, at least 1-2 of the threads I'm reading through about some people's experiences suggest that watching/monitoring NO3, PO4, etc. is highly desirable and I'm not sure how often/how religiously I should do that to get success at this point.

 

(if anyone has halophila or other seagrasses I'd be much obliged........)

 

2. "lower reef/mesophotic reef".   This would be a normal reef tank (I have 3-4 methods of "turn key" instructions that I can go with for setting up a reef, as well as my previous experience, so I think this would be easy) but I would choose stuff from around thre 25-40m range, so I could get by with much less than normal levels of light (maybe just two T5s for 8 hours a day and then actinics the rest of the time).  I'd keep this bare bottom.  Life would be a BTA, maybe a pink skunk clown, and then a few firefish, and some amount of live rock.    Maybe after several months I'll start dabbling in the "deep acros" again.   

 

Anyway, looking forward to folks' thoughts.  Which would you vote for?

 

 

(heck, since some macroalgae and seagrass live this deep, maybe I could have both!)  

 

 

Edited April 14, 2020 by KingOfAll_Tyrants

[Jon Lazar]

I'd go with the seagrass lagoon / planted tank.

[mogurnda]

I'd vote planted tank as well.  With seagrasses, you will want the whole bottom to be deep sand, because they will spread to fill the available space.  

 

I have been very happy with my seagrass tank.  I am growing Thalassia and Syringodium, and they are easier to grow than I expected.  Having real roots provides some real advantages.  They can take up nutrients from the sand bed, which makes them less dependent on input from the water column, and growing roots act as a sink for nutrients.  Also, if everything gets out of control and you get a nasty bloom of nuisance algae, the roots keep the plant alive even if the leaves are completely overgrown.  In my system, nutrients are provided by a heavily fed 90 reef next door, so I have not had to dose anything. 

 

For the macros, fish poop for N and P, along with careful additions of a micronutrient supplement (most are based on Guillard's f/2, and many can be found online), is often enough, especially if you plan to dose CO2 as a carbon source.  You'll want a source of Ca and extra carbonate if you are growing calcareous algae like Halimeda or Penicillus. Based on my experience culturing macroalgae at work, you will want to dose carbon, nitrogen and phosphorous at a ratio of about 150:30:1 for any green macro.  A source of micronutrients, like Florida Aqua Farms' Plant Fuel is helpful in moderation.  The Redfield ratio (106C:16N:1P) is for microalgae, and, at least in my hands, standard nutrient mixes for algae culture cause a phytoplankton blooms.  I use NaNO3 for N, KH2PO4 for P (and K) and CO2 for C (but have also used vinegar). 

 

  

 

 

[KingOfAll_Tyrants]

42 minutes ago, mogurnda said:

I'd vote planted tank as well.  With seagrasses, you will want the whole bottom to be deep sand, because they will spread to fill the available space.  

 

I have been very happy with my seagrass tank.  I am growing Thalassia and Syringodium, and they are easier to grow than I expected.  Having real roots provides some real advantages.  They can take up nutrients from the sand bed, which makes them less dependent on input from the water column, and growing roots act as a sink for nutrients.  Also, if everything gets out of control and you get a nasty bloom of nuisance algae, the roots keep the plant alive even if the leaves are completely overgrown.  In my system, nutrients are provided by a heavily fed 90 reef next door, so I have not had to dose anything. 

 

For the macros, fish poop for N and P, along with careful additions of a micronutrient supplement (most are based on Guillard's f/2, and many can be found online), is often enough, especially if you plan to dose CO2 as a carbon source.  You'll want a source of Ca and extra carbonate if you are growing calcareous algae like Halimeda or Penicillus. Based on my experience culturing macroalgae at work, you will want to dose carbon, nitrogen and phosphorous at a ratio of about 150:30:1 for any green macro.  A source of micronutrients, like Florida Aqua Farms' Plant Fuel is helpful in moderation.  The Redfield ratio (106C:16N:1P) is for microalgae, and, at least in my hands, standard nutrient mixes for algae culture cause a phytoplankton blooms.  I use NaNO3 for N, KH2PO4 for P (and K) and CO2 for C (but have also used vinegar). 

 

  

 

 

 

Thanks!   How deep is your sandbed?  What is your sandbed made of?

 

I was only thinking about a partial sandbed because 1) I'm just getting into this and want to start off slow 2) I did OK with my last DSB (made for yellow headed jawfish) but in my last tank crash I saw lots of crap/unprocessed detritus, and I thought I stirred up the sandbed decently (not too much but not too little), didn't feed that much, and had enough detrivores running around.   But then if the rhizomes grow to fit the space, then that's a bit comforting from that perspective.   

 

 

So yeah I've heard about these ratios, so then NO3/PO4 should be like 1.5/0.05, or do you keep them substantially higher (3/0.1?  higher?).  Also, how do you measure C?  (I heard about calculating it from your KH and pH, but are there better ways for the hobbyist?)

 

Initially I won't have many fish, and my endstate is not to have too many fish (granted this will be a 20 high and so I can't have that many in hte first place.........), which is why I'm a bit concerned about nutrient dosing.

 

Yeah when it comes to dosing I would intend to dose modest amounts of NaNO3 and KH2PO4.   Is there any advantages of using CO2 versus dosing vinegar?   Honestly modest dosing of all of those to my mind sounds like the easiest way to do keep up nutrients.   

 

Anyway, eventually linking a seagrass tank to a big reef (i.e. having it be a big display refugium ) was an idea I was pursuing.  But that will be a while now.....

 

Thanks for the input!

[mogurnda]

It's a 27-ish cube, with about 4" of sand caribbean sand.  It's a mix of coarse and fine (I will try to remember the actual grades).  With a mix like that, the activity of the roots and worms tends to make it stratify, with the coarse stuff going to the top.  Last time I pulled out some plants, there was a massive storm of detritus, so it's definitely in there.  Funny thing is that I never feed that tank, because the slugs only eat the algae, so the debris must come from the plants and, to a lesser extent, from the reef.

 

I can pull up the reference for the C:N:P ratio if you are interested.  I dose N and P at 30:1, which may be too conservative, but it works.  It's easy enough to calculate C when dosing vodka or vinegar, but I just set a pH range when I use CO2 and hope I'm getting it right.  

 

There is a long, slow period when the plants are getting started, and you'll probably see some blooms of Derbesia and other nuisances, but it's pretty easy once the plants have settled in.  I trim the turtle grass every few weeks to keep it from shading everything, and that's about it.

[KingOfAll_Tyrants]

Aha, now I get what you were saying about slug blog.   I looked over it, that's really awesome.  (USG is that facility near Darnestown which houses branches of multiple universities? If so, I've hung out in the library there before).

 

If you have a moment for the 150:30:1 ratio reference, that's cool.  But I've seen it referenced elsewhere in different aquarium fora.   

 

As far as dosing them, can I then say that i should add something like this:

Using Brightwell Neophos (not that I will, just that I have their formula handy), 1 ml NEOPHOS will increase the phosphate concentration in 1 US-gallon (~3.8 L) by ~1.2 ppm, therefore about 1.7ml is necessary to bring my 20 gallon up to 0.1ppm (pretty high by reef tank standards!)

Using Brightwel NeoNitro, 1 ml NEONITRO will increase the nitrate concentration in 1 US-gallon (~3.8 L) by ~5 ppm -> therefore 12ml is necessary to bring my 20 gallon up to 3ppm. 

Using Vinegar, I'd have to use a relatively large amount it seems.   (my guess is over 20ml, but again I'm spitballing.   If it becomes large enough, I may swap vinegar for vodka just to keep down the needed daily amount.  Will ask Randy Holmes Farley......)

 

(as an aside, do you recommend those targets, 3ppm NO3 and 0.1 ppm PO4, or is that too low/high for this kind of tank?  And another random aside, looking at this subject, my previous tank always had PO4 in the 0.1-0.2ppm range but NO3 in the 3 range, at its highest.  It seems I was very carbon limited, and should have dosed vinegar again after stopping it like a year ago.......)

 

And yeah, I think it would be a bit of time to get the plants situated and growing.   The freshwater planted tank folks (e.g. Walstad) recommend getting quick-growing plants in ASAP to outcompete the algae.  I was going to use some caulerpa and other quick growing macroalge to do so, though I'm not sure how applicable that would be for a marine tank.   

 

Just for reference, if a macroalgage or seagrass starts turning red/purple, that's a sign that it's nutrient limited?   

 

 

 

 

Anyhow, moving this forward is then my tenative tank plan:

 

Stuff:

- 20 gallon high

- No sump or overflow. (thermometer, etc. in the main tank)
- Tunze 9004 DC skimmer (I have one sitting around) + small oxydator, mainly for gas exchange
- Maybe about 10lbs of live rock
- Two MP40s (just because have them sitting around. Will keep them on lagoon mode in very low settings)
- Light: 24"Finnex planted+; 1x will be sufficient?
- Tunze nano ATO.
- Seneye reef to keep constant watch on ammonia, co2/oxygen and ph, at least initially.  (debating this vs. apex.  I have an apex brain lying around)

Setup: (note that I've taken several pages from the Walstad freshwater planted tank method - nutrient laden substrate, quick growing plants, then slow-growning plants, CUC and gradual addition of fish, especially noteworthy here because nitrites are not as big a problem in saltwater as in freshwater?)

Sandbed will be 4 inches deep. I'll place a good amount of miracle mud ( it seems there are several products out there that do this - miracle mud, koralagoon substrat, mineral mud.... they probably would be better than something like ecocomplete, because they're made for marine fuges and are therefore more expensive...lol) That being said, if I can get appropriate wild substrate for seagrasses from a vendor, that would be even better. 

Initial plants will be various forms of in-sand caulerpa species. C. prolifera (fast grower), paspaloides (fast), cupressoides (slow grower). I may also try gracilaria and ulva as fast growers, maybe on a piece of rock or somesuch. (heck, maybe I'll throw in a ball of chaeto).  My worry, based on previous experience, is that these will disintegrate in a new tank, presumably because there's not enough nutrients, which is what the miracle mud stuff is supposd to counteract.

 

I was going to try Halophila, but may also try Thalassia and Syringodium based on availability.  I may also try one of the in-sand halimeda species. (Supreme Reefs has big strands)

 

I'll add a CUC fairly soon (if not "start" day, then a within a few days) - astrea snails, a few trochus, small cerinths and nassarius. In total aobut 12 inches of snails for the 20G. I might add a few shrimps.   I loved having a tuxedo urchin but it previously ate all my coraline, leaving my rocks prey for derbasia, etc.

 

I may pour in phytoplantkon (or not - maybe it will be a competitor for my plants???) and/or a large group of copepods.     

 

My first fish (don't know how long I'd wait to add it - Walstad says wait several weeks, but I've been told that's because of freshwater fish sensitivity to nitrite and not applicable in marine tanks and so I should add one hardy one early to be another ammonia source.   My first one will either be a tailspot blenny or a dwarf filefish.   After a few months, I'll add whichever of those I don't get, then add a yellow headed jawfish (love this fish).  And maybe a small school of small cardinalfish.

 

If all goes well, I'll add a gorgonian in a few weeks(Antillogorgia anceps - I've had good luck with them), maybe a favites/favia of some sort (good luck with them).  Maybe even an acro and pocillopora (love the latter genus).   

 

And that will be plenty, maybe even too much, for a 20gallon with a 4 inch sandbed!

Edited April 16, 2020 by KingOfAll_Tyrants

[mogurnda]

Overall, looks like a careful plan.  I don't have time for a more thorough response (dang this whole work thing) but here are a few comments (FWIW).

1.  I use the ratios to determine how much I put in, rather than the steady levels. PO4 in my algae system is always too low to measure.  I look at it like feeding dogs: if the food is gone, they must have eaten it.  I buy dry reagents, use chem 101 to figure out my concentrations, and dose at a ratio of ~30 grams nitrogen to 1 gram phosphorous.  Start at low dose, then ramp up slowly, using test kits to make sure you're not overdoing.  It's different from reefkeeping, where you're trying to reach a constant level.

2. I have found rock to be a liability in a small planted tank.  Takes up  space, stuff can collect underneath it, and always seems to block light in some place.  For a gorgonian, anchor it to a small rock.  I have some Montipora just sitting on the sandbed, and it does just fine.

3.  Go light on the cleaning crew.  Tangs are a no-no (obviously not an issue in your 20g), as are urchins.  I would rather have an ugly algae bloom than add a fish or invert that will mow down your grasses.  Ceriths and Nassarius are good, as are the little columbellid snails.  Astrea would probably be OK, but you will probably want to keep an eye on the Trochus.  

 

That does sound like a pretty full 20 gallon tank.  Might be worth waiting on fish for a short time, just to let the tank settle a bit.   With everything in the water column after the sand, mud and plants go in, there will probably be quite the bacterial bloom for a while.

 

 

[KingOfAll_Tyrants]

Excellent, thanks again Mogurnda!  I really appreciate you sharing your experience.   A few things that I found particularly interesting.

 

3 hours ago, mogurnda said:

Start at low dose, then ramp up slowly, using test kits to make sure you're not overdoing.  It's different from reefkeeping, where you're trying to reach a constant level.

 

I have found rock to be a liability in a small planted tank. 

 

Go light on the cleaning crew.  I would rather have an ugly algae bloom than add a fish or invert that will mow down your grasses.  [don't know if Queen of All Tyrants would agree ) Ceriths and Nassarius are good, as are the little columbellid snails.  Astrea would probably be OK, but you will probably want to keep an eye on the Trochus.  

 

That does sound like a pretty full 20 gallon tank.  Might be worth waiting on fish for a short time, just to let the tank settle a bit.   (Indeed.   What I listed was everything I'm considering, though I doubt I'll actually add more than half of all that). With everything in the water column after the sand, mud and plants go in, there will probably be quite the bacterial bloom for a while.

 

 

 

Also, for the curious (to include myself when I forget what I wrote and look back into this thread for reference), Randy Holmes Farley states 1 tsp (5ml) of vodka has 1g of carbon (10x the amount white vinegar has).   So it seems for the hypothetical 1g phosphorus and 30g nitrogen, I would need 150g carbon (750ml!!!) of vodka, though obviously in a 20 gallon tank that's an insane amount on all sides.   (the planted tank calculator says that to raise phosphate in 20 gallons water by 0.1ppm, I'd need 0.1g potassium phosphate in 10ml of RODI.   Ergo, 3g. nitrogen and 15g/75ml vodka.  (sounds like a lot!)

 

Though again, it seems you don't dose vodka with phosphate or nitrate.  

 

Anyway, a few more little questions.

 

It seems that Trochus will eat seagrasses?

 

The predicted bacterial bloom, then, is a matter of the new tank becoming stable, and I should probably not filter or do drastic water changes to remove bacteria? (much less dose bacteria killing stuff!!!!!)

Edited April 16, 2020 by KingOfAll_Tyrants
missed that he already answered a question that I previously asked!!!

[mogurnda]

23 hours ago, KingOfAll_Tyrants said:

 So it seems for the hypothetical 1g phosphorus and 30g nitrogen, I would need 150g carbon (750ml!!!) of vodka, though obviously in a 20 gallon tank that's an insane amount on all sides.   (the planted tank calculator says that to raise phosphate in 20 gallons water by 0.1ppm, I'd need 0.1g potassium phosphate in 10ml of RODI.   Ergo, 3g. nitrogen and 15g/75ml vodka.  (sounds like a lot!)

 

Though again, it seems you don't dose vodka with phosphate or nitrate.  

 

Anyway, a few more little questions.

 

It seems that Trochus will eat seagrasses?

 

The predicted bacterial bloom, then, is a matter of the new tank becoming stable, and I should probably not filter or do drastic water changes to remove bacteria? (much less dose bacteria killing stuff!!!!!)

I am just lucky that Mrs Mogurnda is a very patient woman.

 

Anyway, the 150:30:1 is just the ratio, not the actual amount.  My recent notebooks are in the lab, and I am stuck working at home, but when I dosed vinegar, I was dosing about 50 ml/day of vinegar, which is about 1g/day of carbon, with N and P in the appropriate proportions.  That was for a 5-tank system of about 60 total gallons.  So, you are right that 1 g of phosphate a day would be a bit much.  Something closer to 5-7 mg a day is more like it.

 

I really am not sure about Trochus and seagrasses.  My turbo would love a chance at the turtle grass, so I tend to avoid large snails.  

 

My worry about bacteria has more to do with that first stage, when everything can get out of whack quickly.  FIlter and skim to your heart's content to get the initial gunk under control, the nitrifying bacteria will be fine.  My concern was mostly that the heavy bacterial metabolism, and effects on water chemistry, during the first week or so would unnecessarily stress the fish. 

 

 I love Walstad's book.  It was the first one that gave me a decent understanding of how planted tanks actually work.  She has some funny ideas, but the principles are solid.  

 

If it were my tank, I wouldn't hurry to start dosing.  Seagrasses and macros can tolerate a little starvation, but cyanobacteria, dinoflagellates and hair algae absolutely LOVE young, nutrient-rich tanks.   Queen of the Tyrants would not approve.

 

[KingOfAll_Tyrants]

5 hours ago, mogurnda said:

Queen of the Tyrants would not approve.

 

 

Indeed this is my big worry.  

 

Seriously, thanks!   I think I may start this next week.  Though rather than my initial 24x12.5x16 tank I might try a 30x12.5x19 (since I have the latter available)

[KingOfAll_Tyrants]

Bringing this thread back from the dead.......  (no tank yet because we're still planning out a massive renovation of the living room of our 2BR2BA.  That said, I am thinking of starting this as a small tank in one of the BA but I'm not 100% decided yet......)

 

What are people's thoughts of a partial deep seagrass bed?   That is, part of the tank (say a half of a 20high) is a DSB with seagrass, the other half is just a normal live rock reef tank?   Will I be setting myself up for any problems?  It would seem not, since people feed their seagrass systems from their DTs.   

 

Thanks!

[Jon Lazar]

14 hours ago, KingOfAll_Tyrants said:

What are people's thoughts of a partial deep seagrass bed?   That is, part of the tank (say a half of a 20high) is a DSB with seagrass, the other half is just a normal live rock reef tank?   Will I be setting myself up for any problems?  It would seem not, since people feed their seagrass systems from their DTs.   

 

 

If you mix the two environments, you'll need high intensity reef lighting for the corals.  Will that fuel nuisance algae growing on the seagrass itself?  Especially in a young tank that has to progress through all those early algae plagues?

[KingOfAll_Tyrants]

Thanks!  My impression is that seagrasses generally need a good amount of light, maybe on par with corals.   (though planted tanks are usually 8000k versus the 10-20,000k usually run in coral tanks.  Even the latter is supposedly mostly for looks - there are people who swear that 6500k is, probably not surprisingly, best for shallow water acro growth.   Me, I don't have the experience to judge).   I am going to go with planted tank spectrum for purposes of this tank.  And actually, at least at first, the non-seagrass half, if I go with this, may not have any coral at all. 

[mogurnda]

I think you might be trying to do too much with a small tank.  Once the seagrass gets going, it needs a good bit of space to spread out, and, assuming you divide it in half, a square foot isn't much.

 

What about the coral bommie look instead?  Get a coral that grows nicely on the sandbed, like a Pocillopora or Euphyllia?

[KingOfAll_Tyrants]

On 7/21/2020 at 9:08 AM, mogurnda said:

I think you might be trying to do too much with a small tank.  Once the seagrass gets going, it needs a good bit of space to spread out, and, assuming you divide it in half, a square foot isn't much.

 

What about the coral bommie look instead?  Get a coral that grows nicely on the sandbed, like a Pocillopora or Euphyllia?

 

Thanks!   That (should use more than a square foot) is good planning feedback.   I think I will then go for the full sandbed.  The motivation was not really for coral, it's just that the required amount of sand (for four inches in a 24x12 system, 60 lbs according to the marine depot calculator, using I believe relatively fine sand?) is a lot and I'm a bit anxious about a number of husbandry things. (but then also anxious to get this started-  i want my jawfish and cardinal fish!!!)   But I think I'll be fine.    

Edited July 24, 2020 by KingOfAll_Tyrants