graveyardworm
Premium Member
Anyone have any thoughts? Most seagrass beds are found in coastal shallow waters, which as I understand is where atleast some of the oceans DO ends up getting skimmed out and taken up by the sandy beaches.
Skimmate as a nutrient source for seagrass
- Thread starter graveyardworm
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piercho
New member
You mean to skim it out of a different tank, and then add the skimmate to a seagrass tank? Or for the same tank you could skim it out of the water column, and then push it into the substrate using a peristaltic pump and a perferorated tubing network in the sand?
I don't know what actually gets skimmed, and except for Shimek I don't think anyone has tried to analyze skimmate. So I don't know what you may be adding by adding skimmate. There could be a dispraportionate amount of phosphate, mercury, or iron in skimmate.
Another consideration is that advection will cause DO to move from the water column into the substrate. So just increasing water motion will help nutrients move into the sediments from the water column, and also make the top aerobic layer of the sediments go deeper than in a low-current tank, all without skimming anything.
I guess if I was trying to enrich a seagrass tank and get grass to grow, I'd add inorganic nutrients instead of organic nutrients. Organic nutrients are more likely to fuel bacterial growth, IMO. But maybe increased bacterial production is your goal?
I don't know what actually gets skimmed, and except for Shimek I don't think anyone has tried to analyze skimmate. So I don't know what you may be adding by adding skimmate. There could be a dispraportionate amount of phosphate, mercury, or iron in skimmate.
Another consideration is that advection will cause DO to move from the water column into the substrate. So just increasing water motion will help nutrients move into the sediments from the water column, and also make the top aerobic layer of the sediments go deeper than in a low-current tank, all without skimming anything.
I guess if I was trying to enrich a seagrass tank and get grass to grow, I'd add inorganic nutrients instead of organic nutrients. Organic nutrients are more likely to fuel bacterial growth, IMO. But maybe increased bacterial production is your goal?
graveyardworm
Premium Member
It was kindof a stupid idea I had late one night and really havent put alot of thought into it yet. I have read Shimeks article, and understand there's alot of unknown amounts of stuff in there. The trick would be getting to the seagrass through the sand bed rather than in the water column, and then how much, but I suppose nuisance algae would quickly let you know when there's too much. It just seemed that potentially skimmate could contian a complete mix of what the seagrass are accustomed to.
Macroculture
New member
If you have access to a freezer that gets cold enough you can freeze the skimmate in ice cube trays and push the frozen cubes (or half cubes) under the substrate to the desired depth and 'entomb' them below the surface. Just try no to go too deep. If you can't find a cold enough freezer you can dilute the skimmate with RO/DI water so you can raise the freezing point.
Macroculture
New member
I was having problems raising seagrass on a large scale and that is the best I could come up with to add water soluble compounds to the substrate once roots were growing. I hated to use the dry plant sticks for land plants in a seagrass tank, they weren't doing what I wanted them to and caused problems. You can use this method to add anything that will dissolve in water and freeze. It works great to introduce Nitrate and Phosphate into the substrate without having it go into the water column too much.
Macroculture
New member
Have tried off and on for a while. I have two 1500 gallon tanks dedicated to three species of seagrass but frequently grow macroalgae in the same tanks at the same time so I am not really giving them the space and attention they need. Also harvesting, planting and maintaining seagrass at the bottom of a four foot deep tank was not something I was prepared for logistically. I tried holding my breath and wearing a mask once but now I just end up lowering the water level when I have to get in and out. Not an ideal solution, I have to use water tanks to hold the excess water that could be better used growing something. I am going to go to larger, shallower tanks with more surface area eventually, but for now I just have to use what I've got.
graveyardworm
Premium Member
Have you experimented with skimmate as a source of nutrients for the seagrasses, or just offering up ideas on how to get it to them? I like your method, but I'm still unsure of potential adverse affect with using skimmate. I dont think I would try this in my lagoon which is skimmed and contains corals, seems like it would be a bit counter productive, but in a dedicated seagrass tank I thought it might have some potential.
Macroculture
New member
I hate to waste anything, no matter what it is. One of the reasons I started culturing macroalgae was to have something useful to do with Nitrate and organic rich water from water changes. Saltwater is expensive and I felt like I was pouring money down the drain. I don't like to 'waste' skimmate, so I try to recycle it whenever I can. It was very counterproductive when I was just adding it to the water column of the seagrass tanks. Ephiphytic micro and marcoalgae bloomed all over the blades of the seagrasses and almost choked them. I found better ways of adding nutrients to the macroalgae tanks about the same time I got rid of most of my fish and corals (thus eliminating the need for protein skimmers). Mostly now when I want to add nutrients below the substrate in small tanks I will use an airline hose to inject them below the substrate. But this was not very feasible in large tanks due to the amount of time it would have taken me. Putting a large number of nutrient rich ice cubes below the substrate was a lot faster and easier than using the airline hose method. I should add though, that you will have to have at least four inches of substrate to give the ice cubes space to melt. Too shallow and they will just 'vent' back to the surface. If you put them too deep and you can disturb your mud bottom or Nitrifying layer. So you can just make the ice cubes smaller or break them into pieces if possible if your substrate is shallow. Fish food does contain heavy metals, which the skimmer will pull out. So over time these metals can build up as fish feed and pass them out with their waste. If you are using a lot of skimmate for any reason in a tank, try to have something that removes heavy metals from the tank, like Red or Black Mangroves or a metal removing filter media.
piercho
New member
Reef world tribal wisdom would be that skimmate would tend to be rich in organic P, and perhaps with a low N
. Steven Spotte showed in the way-back (pre-skimming days) that air bubbled through saltwater attracted organics rich in P to the bubble’s surface. Like I said earlier, besides Shimek, I don't know of anyone who has made a real analysis of skimmate, and Shimek's sample was tiny and some competent chemists questioned his methods. So...what the heck is in that gunk? You know what is in F2, miracle grow, potassium nitrate, and these are not potential bacteria/cyano food like skimmate.I'd agree that I would prefer to make nutrients available to sea grass roots first instead of the general water column. At some expense, a peristaltic pump would be the preferred means to do this, IMO. First, a peristaltic pump meters precise amounts of your nutrient solution against varying backpressure. 2nd, it can do this at highly regulated time-controlled intervals. So, instead of big bursts of nutrients you can meter in a continuous supply of nutrients. With a perforated tubing network laid at the very bottom of the tank before the substrate is put in, you are sure the nutrients are being pushed into the deepest layer of the sand bed. The problem is that a suitable peristaltic pump runs $200 and more. I got my Blue-White metering peristaltic pump ($275 listed) from eBay for $40 in like-new condition, and I intend to use it for exactly the purpose described above in tank2. That pump can just about push fluid through a brick (up to 100 psi). I've also picked up an Aquamedic Reefdoser peristaltic pump array with controller and 3 pumps for $100 used. The aquamedic peristaltic pumps are relatively cheap but also relatively weak, but should be suitable for this type application. So, a diligent DIY reefer can pick these type pumps up for a more approachable cost if you have the time to surf the net for them, and know what you are looking for.
Sorry for the peristaltic pump segue. Controlled input of nutrients into a sand substrate is something I've been gnawing on for a while, and just thought I'd share my cud. As far as introducing organic nutrients like skimmate, I’ve had bad experiences doing this with nutrient-weak solutions of known makeup (acetic acid). Tends to become bacteria/cyano feed and the plants never get a crack at it, IMO. I’d be really hesitant to do it with a concentrated solution of unknown makeup like skimmate, IMHO. But then again, I peed all over the notion of injecting CO2 for seagrass, and some people have shown effective use of CO2 in their particular marine setup, so what the heck do I really know?
graveyardworm
Premium Member
Piercho, when you begin to set up your new tank could you start a thread to describe your methods and process?
As far as dosing is concerned what will you be dosing, N, P, Fe, etc? Are you planing on dosing all of these individually with seperate pumps or will you be mixing them altogether if its possible? How do you think dosing directly to the sand bed might affect its ability to function as DSB, and how might it affect the lifespan of the sand bed? I suspect that you wont get the anaerobic conditions required for NNR. One last question suppose you do get proper conditions for NNR what do you think might become of N pumped directly into or near to those conditions.
I got another one, if your adding nutrients directly to the sand bed how will be monitoring them to know if you've got too much or not enough. I suspect that only traces will be noticeable in the water column if at all.
Of course everyone is welcome to take a shot at answering these questions.
As far as dosing is concerned what will you be dosing, N, P, Fe, etc? Are you planing on dosing all of these individually with seperate pumps or will you be mixing them altogether if its possible? How do you think dosing directly to the sand bed might affect its ability to function as DSB, and how might it affect the lifespan of the sand bed? I suspect that you wont get the anaerobic conditions required for NNR. One last question suppose you do get proper conditions for NNR what do you think might become of N pumped directly into or near to those conditions.
I got another one, if your adding nutrients directly to the sand bed how will be monitoring them to know if you've got too much or not enough. I suspect that only traces will be noticeable in the water column if at all.
Of course everyone is welcome to take a shot at answering these questions.
Fascinating thread. I don't know enough to have any knowledge to contribute, but soon I will be setting up a tank that will be jawfish, macros, and seagrass... or at least my best attempt at that kind of tank! Will begin moving into the house on Sunday, have purchased the tank but will need to build a stand for it.
I have to say I really like the idea of putting something in place that would allow me to target feed the macros and seagrass, if I can do so without compromising the comfort of the jawfish I hope to host.
ej
I have to say I really like the idea of putting something in place that would allow me to target feed the macros and seagrass, if I can do so without compromising the comfort of the jawfish I hope to host.
ej
piercho
New member
My plan is to have a thread on this forum for tank2 â€"œ my second and I expect final reef tank. I have a tank and stand and some other gear accumulated to start tank2, but house projects and out-of-state work assignments are pushing back installation of the tank, at least until spring 2007. I want to keep sea grass and a pretty macroalgae or two in the display tank, along with corals and clams. The main system “filter†will be a turf algae vegetative filter, although I do intend to inject O3, run continuous GAC, and have an air-driven skimmer on this system, as well as a large sand bed volume.
Potassium nitrate is what I intend to push into the sand bed. I will be dosing a known concentration of nitrate solution into a known volume of my tank system, rather than try to dose nitrate up to a testable level. My postulate is that mature reef tanks tend to run a low N
. Even though both nutrients often remain below detectable levels, the nutrient imbalance tends to shift production to algae specialized to compete in low-N environments. I also think this may be a situation that causes some photosynthetic cnidarians to do poorly. My idea is to bump up N and the N while leaving both N and P below detectable levels, making the injected N available first for sea grass production by pumping it into the sand bed, with the excess diffusing up into the water column. The water column will receive a balanced inorganic input through F2 microalgae fertilizer. The plan is to feed the tank live zooplankton fed by live phytoplankton, so there will be residual F2 fertilizer going in with the zooplankton along with the zooplankton pee/poop. I hope most of this F2 and bug pee/poop will get sucked up by the algae turf scrubber, otherwise I’ll run into trouble quickly.
If you are pushing nitrate into the sand bed, it can be used by bacteria in reduced-oxygen gradients of the bed. IMU there is a limit to how much this can occur, and that limit is the availability of organic carbon. Since I’m not adding organic carbon along with the nitrate, I expect the nitrate to mostly remain available for plant uptake, rather than being used by bacteria. I don’t expect injecting nitrate to have any detrimental effect on the sand bed, and hope it will reduce the occurrence of cyano at the surface of the sand bed. Since I’m only injecting a very small volume of a concentrated nitrate solution, I also don’t expect it to have much effect on the oxygen gradient of the sand bed. As far as sandbed "lifespan" and the phosphate-sponge postulate with creeping anoxic levels - I'll refer you to the holy order of BB rock-cooker/boilers over in the SPS forum. I have no doubt that a sandbed can become overloaded with organic nutrient inputs, but I have not experienced this. My experience with my husbandry has been just the opposite. Putting nutrient-saturated sand from an eelgrass bed in to start a tank, it became gradually depleted of nutrients over time.
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graveyardworm
Premium Member
Thanks for the detailed response, I cant wait for the new tank set up. You dont have any concerns with possible heavy metal buildup and the use of F2 as far as it might relate to keeping corals and clams? I have some F2 and can see whats in it, however it doesnt list what quantities of the ingredients are in there.
piercho
New member
Hmmmm....I recall seeing the breakdown for F2 somewhere, maybe in the Plankton Culture Manual? Or maybe just the ingrediants, and not the quantities? I'm across the country from my manual (and home) right now, and won't be back home until 2007.
I expect the algae scrubber to help regulate metal levels in the water column. As far as what accumulates in the substrate, chemists like Farley don't give much credance to Shimek's theory that metal accumulation in the sandbed causes OTS. However, sand is cheap and easy to replace, so if I do get cause to suspect the sand is poisoning the tank, its an easy remedy.
Neither can I. Tank1 is in the basement where visitors don't see it, isn't designed to handle an extended high nutrient load, and is an eyesore of visible plumbing and wiring. But I intend to take my time and set up tank2 much better than I did tank1.
graveyardworm
Premium Member
How long ago did you do that?
