Continual lighting effect on Nano water chemistry

[moses]

It is it necessary to keep nanos lit 24-7 (at least on the refugeium) to prevent ph swings during the night?

Or better yet what is the impact of not doing the 24-7 thing on a nano as far as the tank's water chemistry goes?

Thanks,
Darren

 

[brandon4291]

Some people prefer to light their refugiums in an alternate cycle to the display lights. One benefit of having a refugium that houses photosynthetic organisms is the pH support. Plants have a measurable effect on pH and oxygen production in a tank, especially when they are dense and in a well-lit refugium.
The night phase or the unlit period of a reef tank is subject to low/none oxygen production and lower pH, and a constantly lit or alternating cycle refugium with macro algae counters these undesirable shifts nicely. One might choose to run the refugium continually if stronger oxygen production is needed, such as in a sealed reef, an older reef, or in a reef with a higher fish bioload.

Brandon

 

[brandon4291]

Without the refugium, a nano aquarium may go through some notable pH shifts each evening depending on how its stocked. This can be countered with good liquid buffer support though, and many of the animals tolerate it just fine.

 

[moses]

Thanks Brandon....


If you have been a great help in this and many more of your other posts which I read diligently. Hats off to you for doing what most thought could not be done, and then sharing your experiences with the rest of the world in the form of posts to reefs.org. I for one am impressed with your sealed baffled reefs.

Darren

 

[PFB]

"Without the refugium, a nano aquarium may go through some notable pH shifts each evening depending on how its stocked. This can be countered with good liquid buffer support though, and many of the animals tolerate it just fine. "

I have not noticed this, and I have tested pH at odd hours of the night.
Have you seen this with your tanks?

 

[brandon4291]

My tanks have a very slight shift, usually .2 or so lower in the morning before lights on than what would be found in the evening just before lights go off. no big deal for the corals, but a friend of mine was having greater fluxes of 7.9-8.4 (hand held pH unit) in her 5 g between the day and night cycles and it was also heavily stocked with fish--we thought this required greater buffer support than usual.
pH shifts between the night and day phase is common in reef tanks, with some reporting greater variances in heavily stocked tanks (relative to water column) and especially in tanks where the macro algae is lit under the same schedule as the display tank. One way to resolve that is to alternately light or continually light a refugium. Unless you dose alkalinity at night a few hours after the lights go off, or have better-than-average circulation, it is likely that you too have the same shift but can't tell because of the test kits you use (colored reagents?) This slight shift is a very common occurence in most setups and less pronounced in others, but either way the shift is there to some degree unless you specifically address the -net- production of CO2 from plants/animals during the night phase

 

[brandon4291]

three major factors that affect the measurable pH shift in our tanks:

1. Proportion of respiring animals in relation to water column. Fish in a nano cause the bulk of the load here, and plants (macro algae) will contribute as they produce CO2 during the dark phase.
2. Circulation: good circulation will drive off CO2 stores as they build overnite. A nano stocked with fish has exceptional circulation if these shifts are not measurable on your kits and you are not using photosynthesis nor extra buffer support as a counter measure. Nanos without fish accumulate considerably less CO2 night and are less reliant on these factors to minimize pH swings.
3. Alkalinity support: more ions available to buffer the pH, preventing changes in pH by binding acids as they are produced in the system. Photosynthesis reduces CO2 in the system, and this has a stabilizing effect on pH, sometimes to the point no shift is detectable if the refugium is counterlit and the correct size for the system.

There are many combinations of variables that work together to create a notable shift or a slight shift in pH. Either way, respiration byproducts should have some measurable effect on a system (even as slight as .1-.2 pts) unless you are meeting that production with some kind of uptake or fixation.

 

[PFB]

I thought most people keep their refugiums lit to prevent macro from going in to sexual reproduction, thus resulting in massive die off?
I wouldn’t be concerned with a .1 or .2 change in pH over night, you get more than that every time you do a WC.

 

[brandon4291]

I think the jury is still out on what causes/prevents macro from going into the reproductive phase, continual lighting may help on that but I dont know. I light mine continually only for two reasons, I need the O production during the night phase and also need to prevent pH swings as much as possible. Once I think an overdose of alkalinity liquid (C-Balance) caused my caulerpa racemosa to go into the meltdown mode, but then again maybe it was wilting and dying. Thats the only time my caulerpa has given me trouble, and FWIW Ive never had caulerpa taxifolia go asexual on any occasion--it seems like tough algae altogether.

We should ask a fellow named Jorge on RDO about the sexual phases of macroalgae and how to prevent it, if continual lighting does the trick he would know for sure. Even Dr. Ron Shimek rolls all the questions about macro algae over to him, hes somewhat of a specialist in the field.

Brandon

 

[brandon4291]

--double post