Reverse Daylight Lighting For a Seagrass System?

[algaeguy]

Hi Everyone:

I'm FINALLY about to get under way with assembly of my new seagrass-dominanted system, and I have a few questions on reverse-daylight lighting. Perhaps this subject may have been covered here before, so forgive me if this is redundant.

In every coral/liverock-based reef tank that I've maintained, I employed reverse daylight lighting with macroalgae (traditionally Chaetomorpha) in my sump for harvest/nutrient export. The arrangement worked well, and pH fluctuations were minimal.

Now, with a seagrass-dominated system, I'm wondering if it makes sense to continue to employ this lighting methodology? I am curious if it becomes unneccessary, or even counterproductive, to light the sump with Chaetomorpha on a reverse daylight schedule? Will simply employing a calcium reactor with a controller on CO2 to keep pH dialed in eliminate the need for this? Also, would the addition of fast-growing Chaetomorpha out-compete the slower-growing seagrasses for available nutrients, thus inhibiting growth in the main system?

Am I overly concerned about day/night pH fluctuations in this system?

Thanks in advance for your feedback!

Scott

 

[Samala]

I think your system is going to need CO2 management with dosing or another method (the reactor) in the long term. Especially if you wind up with the plant growth level I'm pretty sure you want.

Chaetomorpha doesnt survive in my seagrass systems. Slowly shrivels away into nothing, even with loads of NO3 dosing. Unless you have some herbivores that really love Chaetomorpha in another system I think it might be, as you said, counterproductive. You'll have two large photosynthetic communities that are both going to consume large amounts of nutrients. Might be a pain to keep up with that demand.

What does everyone else think? I'm comfortable with a 0.1-0.2 pH value drift from day to night.. is that going to be okay for corals?

>Sarah

 

[Samala]

Oh, if you dont have lots of calcifying critters you could do just the usual freshwater CO2 setup: tank, solenoid, pH controller. I dont remember what they tend to run for cost.

>Sarah

 

[algaeguy]

Thanks for the input, Sarah! You've saved me haveing to buy yet another light fixture! LOL

I have flirted with the idea of CO2 injection, but I'm undecided at this point. I figure I'll go with a CA reactor to start to see if I can keep a reasonable pH fluctuation and provide some alkalinity control.

The corals that I will be keeping probably will do fine with slight pH fluctuations (a blanket statement, of course!). Mainly Anthelia, Gonipora, and a few few others, relatively undemanding from a Ca perspective. I figure that I can always be inneficient with my CO2 use in the reactor and divert some directly to the tank, but that's a whole different thing to think about...

Definitely want to experiment a bit!

Thanks!

Scott

 

[Samala]

Sounds good! This is really going to be an interesting showpiece display. I've got some grasses growing specifically with you in mind.

>Sarah

 

[algaeguy]

I am SOOO excited about this! Hope it's up and running when you visit!

Scott