farming macro algae?

[Sen]

My new prop-system is cycling and I wanted to buy some Chaeto and some other macro algae for the fuge. But in Germany they're hard to get. Especially here in the cologne area.

Then I thought about an old kids-pool and the upcoming summer. Would it be difficult to farm macro algae in a pool outside in the sun? Not only Chaeto, I thought of everything I can get (Gracilaria, Botryocladia, Lomentaria, Scinaia etc.)

I have two shell-shaped kids-pools an a 6000 l/h (1500 g/h) pump - the current will be no problem. I thought of building a small "greenhouse" covered with foil (just big enough to house the tanks).

But there are still some questions.

What about the temperature? In the summer we get outside temperatures around 30 - 40° C (86 - 104° f). The min-temperatures can be around 10° C (50° f). What is the temperature-range marco algae can deal with. Heating is not a big problem but what about the hight temperatures?

Then there is the water. I have a ro/di-unit, but in the summer, there will be a lot of top-off. Would it be better using normal freshwater to mix the seawater? There ist more NO3 in it. But there also a lot of silicates? And - do the tanks have to cycle? Is live rock needed? I mean, to get a good grow-rate I have to add nutritions,, may be NO3, CO2... things I would never add to a tank with other marine organisms.

That leads to the next point. What can I use as "fertilizer"? I found the thread about CO2 yeast. May be I can realize something like that.

Ok, I know, these are a lot of questions. But this idea came up to me just today. And it has to be cheap. I'm building a prop-tank for Corals at the moment.

Do you have any answers or ideas for me?

 

[graveyardworm]

Your two biggest problems are going to be overheating, and maintaining stable salinity. The tubs should be covered in some fashion to prevent rain from diluting the water. A large box fan blowing across the the water surface will help to keep the temp down but will increase evaporation.

Since this is only going to have macros in it you could add nutrients with off the shelf fertilizer if aqurium type products arent available.

I would try to keep the temp as stable as possible. I would think though that the macros could tolerate temps as low as 70, and as high as 100. Shallow water lagoons and tidal pools can get see a large temp swing throughout the day.

 

[Samala]

I agree with David, the temperature issue is going to cause some concern. You might consider putting green house cloth over the ponds to cut down on irradiance and to keep the prop system a few degrees cooler. Of course there's the trade off on less light overall.

While there are definitely instances where macroalgae might have to suffer through 85F+ temperatures in the shallows of tropical areas, it is not exactly an ideal situation. You may have plenty of macroalgae survive it, but they may not thrive in it and grow to the level you would consider worth the trouble of farming. In the good weather the outdoor situation may be ideal though, so if I were you, I would still attempt it.

You will need excellent control of nutrients to avoid phytoplankton blooms, diatom blooms and cyanobacteria blooms.. all of which can smother your farm. I would definitely suggest the use of heavy aeration to keep pH in line and CO2/O2/etc in balance. If it were me, I would hook up a drip line of NO3, PO4 and be sure to dose the micronutrients to keep things humming along.

Overall sounds very interesting. I'm sure we'd all love to be in the loop as you plan out this venture. Any new project with a plant focus would be a great addition to this forum.

>Sarah

 

[Sen]

Thanks for your thoughts.

I think the heat-problem will be the most difficult to solve. One idea is to dig a hole about 1 m (3.3 feet) and put a long, flexible tube in it. Then I could pump the saltwater directly through it. I did a little bit research on this and found that we reach max. temperatures of 15° C (59° f) in this depth here in my area. But the hole has to be large to get enough tube in there.