Gas exchange

[codyreed29]

I was wanting some information on gas exchange. I am going to have a glass top on the display aquarium (29g). I will have my sump (20 h) open and have a fan and some holes drilled in my tank stand.

Should I go for no top on the tank.

 

[philosophile]

No glass top. If you're worried about jumping fish get a screen.

 

[Subsea]

+10 on no glass top.

 

[Badbrad8500]

No glass top, buy netting. That gutter guard stuff from Lowes or HD works pretty well.

 

[Aquarist007]

Are you going to run a protein skimmer in the sump
What kind of lighting will you have?

 

[reefgeezer]

I seem to remember reading somewhere that: 1) Gas exchange occurs to equilibrium @ the surface whether or not there is a glass top... unless it is completely sealed; 2) Increasing light penetration and evaporative cooling caused reefers to discard the glass tops; 3) It also occurs in the surface of the sump; and 4) A skimmer may drive off excess CO2 and help if O2 is below saturation.

 

[Aquarist007]

Protein skimmer and the sump can be enough for aeration.
If running uncovered strip led,s then you need a glass top
If running temp high then I remove part of the glass top and direct a power head at the surface for heat exchange

 

[codyreed29]

I will have a protein skimmer in the sump. The top will cover all but an inch in the rear for the over the top style return nozzle.

Are you not supposed to run leds without an optic or glass in between.

 

[codyreed29]

I think I will be OK with open sump and not completely covered.

 

[wooden_reefer]

I was wanting some information on gas exchange. I am going to have a glass top on the display aquarium (29g). I will have my sump (20 h) open and have a fan and some holes drilled in my tank stand.

Should I go for no top on the tank.

In general, gasous exchange is the most critical at the air-water interface of the tank and the sump etc.

Otherwise, moving of air within the gasous phase has more to do with temperature than gasous exchange into water and from the water.

Gases dissolving into water is the slow step, gas transport to near the surface is the fast step.

 

[Aquarist007]

QUOTE=codyreed29;23160920]

Are you not supposed to run leds without an optic or glass in between.[/QUOTE]

It depends how close to the surface they are. Salt creep will shorten the life of the unit for sure
If they are going to be close to the surface then you need a glass top

 

[Aquarist007]

In general, gasous exchange is the most critical at the air-water interface of the tank and the sump etc.

Otherwise, moving of air within the gasous phase has more to do with temperature than gasous exchange into water and from the water.

Gases dissolving into water is the slow step, gas transport to near the surface is the fast step.

"I can say without equivocation that skimmers , your topic of choice/hijack here ;not mine, enhance gas exchange even with lot's of ripple and agitated open water.

My system has over 50 square feet of open water ,heavily agitated at the surface. Nonetheless, turning on the skimmers with low CO2 air feed via a CO2 scrubbers attached to the air intake results in an increase in pH due to lower CO2 levles in the aqurium water, pH 8.0 to 8.15 diuranl sewing without it ; 8.15 to 8.25 with it. The gas exchange is very significant and obvious. Many others have similar results with fresh air intakes .

I have not used a wet and dry for aeration. As noted it earlier it might work if you don't mind the nitrate production and may be a good source for NO3 it in terms of relevance to this thread but it needs to be quite large to match a good sized skimmer in terms of gas exchange ,IMO. "
TMZ (Tom)

 

[codyreed29]

The skimmer are rated fo almost double compact sca 301 65 gallons one a 30 to 35 gallon system. As well as alot of surface agitation and water movement.

 

[codyreed29]

My leds are about 10 inches above water line and will be higher on refugium. I have optics on half the fixture.

 

[wildman926]

I will have a protein skimmer in the sump. The top will cover all but an inch in the rear for the over the top style return nozzle.

You will be fine with that setup. As someone already pointed out, your tank is not completely sealed and the sump and the protein skimmer will be all you need.

Are you not supposed to run leds without an optic or glass in between.

No issues with the glass. There is only a 12% reduction in par when using glass. You can read that HERE.

 

[ThreeMoneyJ]

I hav a few tanks up and running. Open, screen top, and glass top. All with a sump and skimmer. In my house the top over the tank has zero effect on ph. When I do see a change in ph it has to do with opening windows.

 

[codyreed29]

12 percent par loss is something I wasnt thinking about. But with a 250 watt mh and 4 24 watt t5hos I dont think its gonna make much diffrence.

 

[reefgeezer]

12 percent par loss is something I wasnt thinking about. But with a 250 watt mh and 4 24 watt t5hos I dont think its gonna make much diffrence.

It's not the number of photons (PAR) lost to a regular glass top, it's the spectrum that is lost. If my ever more limited memory serves, the photons that regular tempered glass tops block most are in the blue range. Starfire (Low iron) glass helps I think. -

 

[codyreed29]

Did you look at the link it says

325 par no top and 305 with glass top.

Par loss 12 percent.

 

[reefgeezer]

Did you look at the link it says

325 par no top and 305 with glass top.

Par loss 12 percent.

As this post is in the Advance Forum, I'll respond. I have read many articles concerning light and corals. All were much more advanced than the link referenced. Really..."here's some readings from a guy"... What was the spectrum of the light used? What type of glass was used: plate; tempered; low iron; etc.? I could go on.

PAR is not the last word on light quality. PAR is the measure of all photons in the visible light spectrum. Photons mostly in the blue end of the spectrum are used by corals for photosynthesis. Even if the number listed in the link is accurate, if the 12% loss consists of photons in the blue spectrum there could be issues, particularly if lighting is marginal before the loss.

I'll stipulate there's no real reason to worry about spectrum loss with LEDs that are heavily weighted to the blue end anyway other than wasting energy. It's even less of an issue on small tanks that are easy to light. However, a 12% loss could be substantial when lighting a large tank.