Paul G
Active member
Today's numbers
pH: 6.7
ORP: 526 mV
NO3: 0.4 ppm
PO4: 0.10 ppm
Fe: 0.16 ppm
K: 40 ppm
dGH: 3.1
Ca/Mg: 36/20 ppm
dKH: 7.9
The DO cycle over the last six days below. Last Tuesday AM I repositioned the return vents toward the front, angling them up a bit to increase the ripple. This simple measure illustrates the effectiveness of surface agitation in entraining air, increasing the oxygen tension. The DO is sustained well enough through the dark hours that the air pump is not required until the COD notch. I've always had the rule "ripple, not chop" in the interest of CO2 retention. This is more agitation than permitted in the past. Utilization rate will disclose how lossy this ripple is. The DO contour just now suggests that the morning rise of photosynthetic O2 tracks the light more closely. This is likely due to higher overnight O2 retention, even though the COD notch depth has not changed. Note also that yesterday's peak O2 hit 10.2 ppm, and that's with more reduction in the light! Though there is some enhancement of the air-water interface, the rise in DO is largely a function of photosynthesis, i.e. carbon fixation, so it is being controlled by the plants. By the way, aeration comes on automatically below 5.5 ppm O2, and there is still a small pH spike there, but complete erasure of the COD notch is a battle I have stopped fighting.
Again, it looks like production is stimulated more readily by carbon availability than by light intensity. There must be a point at which diminished energy input is limiting, since with no light there is no photosynthesis, and clearly DO corresponds to the light cycle, as the graph shows. With the amount of control over the energy input that I have here I am still not finding that limit. But the change in pH and KH has significantly increased the CO2, and the DO does seem to show high sensitivity to that.
I like the timing and intensities of the lights in the current program. The tank is not too dim, but does not glare. I have the energy dialed down more than ever before, but it's pleasantly bright. The growth of periphyton Charophyta does respond to the light; the latency is low with increase and high with decrease. Turn the light up, it takes a couple of days to get a good population of green alga on the glass and rocks; turn the light down it takes a week. However, it cannot be altogether eliminated as long as the aquarium is lit.This pattern does not seem to be affected by changes in pH (CO2). The throttling effect for algae in the aufwuchs is in the lighting.
Macrophyte production is switched on and off by light, but growth does not rapidly correlate in an obvious way with intensity. However, the rate of production responds immediately to carbon availability, and this can be seen in the DO trace. Now, over time, surely, the production rate must correspond with the prevailing PAR intensity, but the practical throttling effect for plants is in the CO2 delivery.
pH: 6.7
ORP: 526 mV
NO3: 0.4 ppm
PO4: 0.10 ppm
Fe: 0.16 ppm
K: 40 ppm
dGH: 3.1
Ca/Mg: 36/20 ppm
dKH: 7.9
The DO cycle over the last six days below. Last Tuesday AM I repositioned the return vents toward the front, angling them up a bit to increase the ripple. This simple measure illustrates the effectiveness of surface agitation in entraining air, increasing the oxygen tension. The DO is sustained well enough through the dark hours that the air pump is not required until the COD notch. I've always had the rule "ripple, not chop" in the interest of CO2 retention. This is more agitation than permitted in the past. Utilization rate will disclose how lossy this ripple is. The DO contour just now suggests that the morning rise of photosynthetic O2 tracks the light more closely. This is likely due to higher overnight O2 retention, even though the COD notch depth has not changed. Note also that yesterday's peak O2 hit 10.2 ppm, and that's with more reduction in the light! Though there is some enhancement of the air-water interface, the rise in DO is largely a function of photosynthesis, i.e. carbon fixation, so it is being controlled by the plants. By the way, aeration comes on automatically below 5.5 ppm O2, and there is still a small pH spike there, but complete erasure of the COD notch is a battle I have stopped fighting.
Again, it looks like production is stimulated more readily by carbon availability than by light intensity. There must be a point at which diminished energy input is limiting, since with no light there is no photosynthesis, and clearly DO corresponds to the light cycle, as the graph shows. With the amount of control over the energy input that I have here I am still not finding that limit. But the change in pH and KH has significantly increased the CO2, and the DO does seem to show high sensitivity to that.
I like the timing and intensities of the lights in the current program. The tank is not too dim, but does not glare. I have the energy dialed down more than ever before, but it's pleasantly bright. The growth of periphyton Charophyta does respond to the light; the latency is low with increase and high with decrease. Turn the light up, it takes a couple of days to get a good population of green alga on the glass and rocks; turn the light down it takes a week. However, it cannot be altogether eliminated as long as the aquarium is lit.This pattern does not seem to be affected by changes in pH (CO2). The throttling effect for algae in the aufwuchs is in the lighting.
Macrophyte production is switched on and off by light, but growth does not rapidly correlate in an obvious way with intensity. However, the rate of production responds immediately to carbon availability, and this can be seen in the DO trace. Now, over time, surely, the production rate must correspond with the prevailing PAR intensity, but the practical throttling effect for plants is in the CO2 delivery.
