Best fertilizers for Gracilaria

gracilaria

Junior Poster
Jun 14, 2007
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Hi,

I've been producing large amounts of Gracilaria fertilizing with about equal amounts of NH4NO3 and (NH4)3PO4 once a week. I help produce the Gracilaria for feed for abalone and have been seeing some epiphytic growth of green filamentous algae. Is this a good ratio or should I reduce the amount of phosphate because I've heard the red algae don't require as much/or any of it? What about KNO3? Would the Gracilaria get better growth, less fouling from green algae with KNO3? I'd appreciate any guidance here. Thanks!

Christine
 

Professor Myers

Guru Class Expert
Aug 24, 2006
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gracilaria;18125 said:
Hi,

I've been producing large amounts of Gracilaria fertilizing with about equal amounts of NH4NO3 and (NH4)3PO4 once a week. I help produce the Gracilaria for feed for abalone and have been seeing some epiphytic growth of green filamentous algae. Is this a good ratio or should I reduce the amount of phosphate because I've heard the red algae don't require as much/or any of it? What about KNO3? Would the Gracilaria get better growth, less fouling from green algae with KNO3? I'd appreciate any guidance here. Thanks!

Christine

Reduce the PO4 to a 3 to 1 ratio, and you may be able to work it down from there. While red algae don't require as much I don't believe it can be eliminated all together for Gracilaria. I wish I could be more specific, but it's been quite awhile since I've done any tinkering with macro algaes, and they were never really my field. Cultivation has come a long way since then. HTH. Prof M
 

Tom Barr

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Jan 23, 2005
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I'd suggest less PO4.
No NH4, use KNO3 or Ca(NO3)2 instead.

All marine macro algae do well with higher NO3 than you can stand than with NH4.

You can still add a trace amount of NH4, but a few small damsels etc will do the same job and be better at all.

Iron is a big one.

I'll have the marine trace iron out here in 3-4 weeks.
For now, use DTPH based iron, Tropica is ideal and far better than other marine Kent and other junk they sell.

Regards,
Tom Barr
 

gracilaria

Junior Poster
Jun 14, 2007
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0
1
Thanks Prof M and Tom for your replies. I will try reducing the PO4 next time. So, should I just keep the NO3 amounts the same from what I had been using, but with the KNO3 instead? The problem is is that I have very large tanks that I am dealing wtih (about 3600 gal), so using products like Kent are not practical. I am not familiar with DTPH or Tropica, but will look into them. We normally use regular agricultural fertilizers since we generally use 200-300g per dosing, per tank.

Thanks for your advice,

Christine