Lighting and phtosynthesis question

[mkt]

anybody knows if there any relation between the ability of the plants to photosynthesis and the frequency spectrum of the lights?

Reason for asking is plants do not bubble and the bulbs are about 7 months old...

[Plantbrain]

It's not the spectrum, it's the intensity, it's unlikely that light your problem.
Look at CO2 always first. Then NO3, K, PO4, GH and finally traces.

Generally plants will pearkl well if you add traces, KNO3 and CO2 to about 20-30ppm for the full lighting period.

If you do that, your plants should start pearling again. Since they pearled at one time in this tank, these are the most likely potential issues.

If you are not dosing KNO3, doing large frequent water changes etc, you might consider it. It will produce vigoruos plant growth, and more O2.


Regards,
Tom Barr

[mkt]

[quote:e31dfe3d78="Plantbrain"]It's not the spectrum, it's the intensity, it's unlikely that light your problem.
Look at CO2 always first. Then NO3, K, PO4, GH and finally traces.

Generally plants will pearkl well if you add traces, KNO3 and CO2 to about 20-30ppm for the full lighting period.

If you do that, your plants should start pearling again. Since they pearled at one time in this tank, these are the most likely potential issues.

If you are not dosing KNO3, doing large frequent water changes etc, you might consider it. It will produce vigoruos plant growth, and more O2.


Regards,
Tom Barr[/quote:e31dfe3d78]

Thanks tom - funny thing is that NO3 was around 20ppm, PO4 i think 0.2 and dosing flourish trace. PH was around 5.9 and KH around 2 so the CO2 is actually quite high! That's the reason I suspect that the aging bulbs are the problem...

Anyway will try per your suggestion when I change the water.
Much appreciated!

[chua]

What about your K?

Maybe you PO4 may not be sufficient too.

[CT]

how much lighting are you using? what is the size of the tank?

[Plantbrain]

Unkless you are the low end of the lighting range, 1.5w or less etc and use commom NO FL's bulbs, the bulb issue is unlikely.

Look elsewhere. When in doubt, do a water change and add the nutrients back and check the CO2(especially at night right before the lights go off), then you can rule out a few things. What is your GH? and How much light do you have now?

Regards,
Tom Barr

[mkt]

288W or ~2.8 W/gallon and have been dosing K + P quite consistently ( to prevent green spot algae ) there's virtually no algae - that's why I'd thought the tank was ok in terms of nutrient balance.

However I noticed that the hairgrass seems to be growing longer - which I think maybe this can be attributed to the diminishing intensity of the PL lights...

GH is about 2-3 degrees.

Right now I have to de-gas( of CO2) the tank with an air pump during lights off so that the fish won't get suffocated! btw the population is mainly small fishes ( rummy nose, cardinals, shrimps, cories ) - totalling to about 50-60 denizens

Will be changing a couple of bulbs ( to see if it's light related ) and carrying out the water change + nutrient addition sometime this week.

Thanks guys!