Try 1 hour before.

Regards,
Tom Barr

I have basically sort of the same question. thought it wasn't worthwhile opening another topic...

I see that at 07.00 am, the plants are standing straight towards the surface and their areleaves folded. at 11.30 am, the tops of stem plants are curled towards the front glass, likely because there is light from the outside. The leaves of my proserpinaca are now instead of folded, curled downwards.

I just wondered whether it would make sense to turn the CO2 on from 09.00 am or so, because clearly something is happening between 07.00 and 11.30, most likely the plants are starting to slowly assimilate. but since the CO2 turns on one hour before the lights turn on (which is at 14.00 pm) could there be a possible shortage of CO2 in the hours begore the lights come on? When the lights are on, the CO2 is stable 6.0 and the drop checker is light green. at 07.00 am the pH is 7.0.

any thoughts?

yme

I'm trying a different approach on CO2. The reason we turn off the CO2 at night is so we can run it very high during the day, but give the fish a break by reducing it at night. But, to avoid algae, stable CO2 is an advantage. So, I now have my CO2 set to about 15 ppm, instead of 30 ppm, and I run it 24 hours a day. I also only have 1.6 watts per gallon of light, so the demand for maximum CO2 concentration isn't as great.

I have had my tank on this system for only 11 days now, so no conclusions are possible, other than that I don't see a problem yet.

The other reason not add CO2 too early, the O2 is lowest at the pre light/dawn time.

Lower O2 and high CO2 are bad combination.
High O2(from plants during the day) and high CO2 are not.

I have a light CO2 curve that estimates the min levels of CO2 required for non CO2 limiting growth for a given light intensity. At 1.6 w/gallon, that's pretty low. I really doubt you'd be limited for CO2 at 15ppm.

At 4-5x the light, you most definitely would be limited.
Most folks about the time of PMDD used 10-15ppm(1995-1996) but also had light levels at 1.5-2w/gal at most.

10-15ppm worked pretty good.
Things changed though.......

This goes back to the idea of less light is better if you seek easier management of CO2 and thereby nutrients.

Still, adding 30ppm is not that difficult and provides a lot of wiggle room for error.
The levels beyond the limiting concentration are inconsequential as far as algae are concerned.

So if anything below say 14 ppm of CO2 is limiting, you can have 15-30ppm of CO2 and never have any issues.

It's when the levels are below that when the lights are on we see issues, especially the initial 1-2 hours.

Plants will just sit there and wait until there's enough CO2 and then start growing.
But not the algae.

They can respond to change much faster.

The key is not allowing the plants to be limited other than with light.
You can do the same type of thing with CO2 in a non CO2 system also.

BTW, those nice ADA tanks, they have low light and many push the CO2 above 15ppm, way above in several cases I've measured.

Even with a wet/dry my bubble rates are similar when I dissolve 30ppm

YME,

Plants will bend towards and try and predict when and where the light is going to come from. This is true for most plants even without light, sunflowers will turn 180 degrees and wait for the sun to rise.

A small amount oif light will induce the plants in your tank to bend towards the light, they are doing anything.........yet, but are waiting to grow.

If it takes longer than 1 hour to go from ambient to 30ppm, then you need to rework your CO2 delivery method.

It's not responsive enough.

Regards,
Tom Barr

Using a conventional drop checker to measure the amount of CO2 in the water doesn't allow us to know that we are reaching 30 ppm during the first hour of high lighting. The drop checker takes a couple of hours or so to reach the same concentration as the tank. With that tank concentration rising, it would have to take the drop checker more than an hour to reach a final reading. Perhaps monitoring the pH of the tank water, with a pH probe, would be a way to verify that we do reach the 30 ppm of CO2. This doesn't mean using that pH reading to calculate the amount of CO2. Just look for when the pH stops rising, then the amount the drop checker shows when it reaches equilibrium with the tank, with the tank pH still at that same value, is the amount of CO2 we had at that time. Once we find that we are successful in reaching 30 ppm in the first hour of lights on time, we can stop monitoring tank pH and just repeat the test occasionally, in case the tank water circulation is changing.

That's why I like my custom made CO2 probe

We used some liquid CO2 references the other day and it's dead on inside 5 minutes.

But you can use the two part system as you suggest, drop checker with pH probe to get to within 5ppm or so.

Regards,
Tom Barr

Thought I would post after being patient and diligent in the new dosing routine.

I can happily say that the years of occurance of BGA, Staghorn, GDA, GSA, well you name it , are all but virtually non-existant now. I do still get random little spots of BBA, usually on the anubis or shells. But if that level of algea is unavoidable then trust me I'll be more than happy. I do find that if I do not prune and allow excess dead growth to propogate, that is when algea starts to reappear. Now all of my plants are growing well. I only have issues with the Amazon Sword that is not as healthy as it should be. New leaves grow in fainted with dark veins, and old leaves become curled and elongated. All of my other plants are doing well. The Ludwigia palustris, repens, and cuba are absolutely thriving. The Cuba was starting to grow out of the tank (24" H) and I was able to take four stalks and prune into eleven. The Ludwigia glandulosa for me is a little slower in bouncing back but it is making its way back. One of my Anubias coffefolia is actually starting to bloom. All of this actually got me excited enough to go out and replace my damaged camera so I can take pictures now.

Thanks again for this site. Without it this hobby would still be a headache rather than the now enjoying experience.