What time of day do sps utilize available Nitrates?

[R_Mc]

Hi all, I run a bare bottom system with a high bacterial population. My nitrate levels have been 0 for a while now (despite heavy feeding). My fish are fat and healthy and I'd rather avoid putting more food in the tank as I'm not measuring for everything else that's coming in.

To raise my nitrates I've started dosing KN03. I dose using a 0.15cc spoon and have roughly 38g of system water. This means that each spoon raises my nitrate levels by 1ppm. To test the rate of nitrate reduction I dosed two spoons last night at 9pm and measured 1.75ppm nitrate on the test kit. This morning at 9am I read 0.5ppm. So, my rate of nitrate reduction is pretty rapid.

My question is, when can coral best utilize free nitrate? And also, does an acropora's nitrate uptake differ from an algae's throughout the day/photoperiod? Are coral taking up nitrates as part of the zoox photosynthesis, or is it absorbed into the tissue for other purposes.

I'd like to automate my dosing, but I'm wondering if it would be better to dose the full amount say...during light on, or during lights off. What I don't want to do is dose kno3 just to feed the bacteria.

Thanks!
Rob

 

[reefmutt]

I'm not a biologist, so I'm not going to try to answer your specific questions, but imo, it doesn't really matter when you dose.. As long as you maintain measurable nitrates in the system, corals and bacteria are going to consume it..
Personally, I have always dosed my nitrates in the morning..

 

[reefmutt]

I love the smell of nitrate in the morning!!!

Sorry couldn't resist..

 

[Spslvr]

We think peak daylight.... And also have suspicion that excess nutrients leading to browning occurs at night....

 

[reefmutt]

Hm! Interesting. Thanks.

 

[jroovers]

We think peak daylight.... And also have suspicion that excess nutrients leading to browning occurs at night....

Interesting... so if I were going to dose nutrients in any form (fish feedings, AA's, coral foods, etc.) might actually be better to do so during the "day"? I've always dosed foods during lights out when polyp extension was maximized assuming thats when things would be most beneficial to the corals...

 

[Spslvr]

Aa's, foods and nitrates serve different purposes

 

[Acronic]

We think peak daylight.... And also have suspicion that excess nutrients leading to browning occurs at night....

Its important to consider that corals have diel cycles (and seasonal) but assuming most people keep relatively constant temp and light atmospheres, it's hard to determine what influence that has on the seasonal patterns.

Corals have two modes of obtaining energy, autotrophic and heterotrophic.

autotrophy (food from light via symbiosis with zooxanthellae)
zooxanthellae photosynthesize obviously during the day. Which provides the coral host with energy rich carbon (sugar) but is nitrogen deficient.

heterotrophy (food from feeding on zooplankton ect)
After corals feed they produce metabolic waste that is nitrogen and phosphorus rich which the zooxanthellae use and the cycle repeats.

Figuring out the autotrophic cycle is relatively easy considering the sun rises and it sets. Of course with some caveats relating to weather and water turbidity ect.

However, figuring out the heterotrophic cycle is more complicated. Many variables change seasonally, daily and instantaneously. Flow bringing food to the corals, zooplankton rising from the depths at night, predation on polyps all play a part in determining a corals heterotrophic cycle. Which would vary location to location. Generally this occurs under the cover of darkness though. Which supports SPSLVR's theory of zooxanthellae browning at night as they feed off the corals metabolic waste.

So, oxygen... A coral tissues boundary layer will be supersaturated with oxygen during peak photosynthesis (great for calcification) and it will be anoxic at night (bad for calcification). Which supports SPSLVR's theory of accelerated uptake during the peak photoperiod.

But if only it was that simple There is a time lag on a corals ability to process the fruits of a function.

Corals are simple beings in that they can't multitask very efficiently. Therefor, when one metabolic function starts, another stops. So when a coral captures prey, it takes all its energy and allocates it for the intake of water to puff out its polyps, muscle contractions and nerve synapses firing its nematocytes and produce mucus to "reel" in the capture and digest it. It has been assumed that this re-allocation of energy actually hampers calcification short term.

I guess in short, figuring out what you are trying to achieve by dosing nitrate will determine when to dose


:beer:

 

[R_Mc]

Thank you, that was very interesting to read.

If my goal was to maximize growth...let's say it is. Then my take away from the above is that I would be best served by having coral tissue at peak nitrate saturation when the coral reaches its photosynthet8c peak. Let's say that occurs 30 minutes after lights on. To me, that means that I should dose maybe 30 minutes prior to lights on. I figure that this would give time for the nitrate to be evenly distributed in the water column and for the coral tissue to take up the high concentration of nitrates. I'd also take this to mean that I should dose all at once prior to lights on rather than dosing smaller amounts over a longer period of time.

That's of course assuming that autotrophy is the only, or at least the most efficient way that coral might use nitrate.

 

[Spslvr]

We are playing around with manganese dosing atm seems to be yeilding some nice results, nitrate dosing seems to be a bit more of a gamble, sometimes seeing great results other times seeing problematic issues like cyano and rtn, we have recently began experimenting with aa's of various blends and concentrations, mixing them with aspartic acid and vit c, my advice would be if you want to dose no3 do it during the day also adding some po4 can help aswell, to further complicate the issue what type of lighting are you running? Where do you keep your kh? These seem to be important when it comes to nutrient dosing, the brighter the light the higher the nutrient....

You can also jump onto our thread tittled the farm under sps keepers theres heaps of info in regards to this topic on there...

 

[Acronic]

We are playing around with manganese dosing atm seems to be yeilding some nice results, nitrate dosing seems to be a bit more of a gamble, sometimes seeing great results other times seeing problematic issues like cyano and rtn, we have recently began experimenting with aa's of various blends and concentrations, mixing them with aspartic acid and vit c, my advice would be if you want to dose no3 do it during the day also adding some po4 can help aswell, to further complicate the issue what type of lighting are you running? Where do you keep your kh? These seem to be important when it comes to nutrient dosing, the brighter the light the higher the nutrient....

You can also jump onto our thread tittled the farm under sps keepers theres heaps of info in regards to this topic on there...

I eagerly await your findings on manipulating "The Hula Twist"

 

[R_Mc]

Thank you again, I'll dose during lights on. I'm also dosing a custom carbon mix of vinegar and vit-c as well as an AA mix of aspartic acid, glutamic acid, and sodium silicate. I'm running a custom led fixture, 120w +30w vereo for 7 hours daily. Hard to tell what's doing what - but I'll definitely check out your thread.