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Co2 timing vs pH/lighting schedule

Franks

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I'm nearly finished with tuning my Co2 injection. My lighting is a Radion XR15FW using EcoTechs plant growth lighting schedule for 6 hours. This turns on at 2pm and ramps up to a max intensity (70%) by 5pm and then it slowly reduces to 8pm. At 8pm-10pm the light runs at 4% to barely illuminate it.

Here is my pH profile:
20th February
9am 7.2pH - baseline
12pm - Co2 injection starts
1pm 6.6pH
2pm 6.4pH dc green
3pm 6.3pH dc green
4pm 6.2pH dc slightly yellow
5pm 6.2pH dc yellow
6pm Co2 injection stops
8pm 6.4pH dc yellow and end of plant growth lighting.
8pm-10pm - extremely low light.

My observation here is that although im not dropping 1pH point by lights on, it doesn't necessarily matter as the lighting is on a slow ramps (which I find wakes up the plants slowly so their consumption of Co2 won't be high). By 5pm, lighting is full and I've dropped 1pH.

Is this the most optimal injection or should I aim for a pH drop of 1 as soon as the lights turn on. This would mean injecting 3 hours before and turning off injection 3 hours before lights out?

Any advice? Plants are pearling well but lots of them are new so not really ready to consume yet.

Thanks
 

Zeus.

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I always aim to get the target (lowest pH reading) for lights on then keeping it stable to within 0.1pH for the rest of the CO2 period, CO2 on 3 hours before lights on sounds about right for 200litre tank IMO. After lights have been on and CO2 stable for 4-5hrs with high light intensity plants will have had their fill of CO2, so CO2 can go off (as advised by @ceg4048 )
 

Franks

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Cheers Zeus. I'm going to shift injection forward by an hour and observe/log pH again.

It seems the water holds the Co2 once saturated so turning off the gas early shouldn't impact, especially if the plants have had their fill.
 

ceg4048

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CO2 on 3 hours before lights on sounds about right for 200litre tank

Actually, 3 hours to drop the pH 1 unit is too long, but it's a double edged sword if you have critters in the tank. Turning the gas on an hour earlier is the best compromise, I suppose.
Again, this timeline may be exposing something less than perfect about your flow/distribution or diffusion technique. Ideally it should only take about an hour.

If you're an over-the-top fanatic like me, using matter/anti-matter di-lithium power cells, it takes about 20 minutes.

Cheers,
 

Franks

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I also think the same but I've tried inline and in tank diffusion and the bubbles produced are extremely tiny and tend to stay suspending in the water column rather than float to the surface like you see on some setups. Both methods have approximately the same Co2 saturation time. In terms of flow, it's huge. I'm running a SunSun canister and everything sways, I have no dead spots. I use a spray bar pointing to the front glass and intake is underneath the outlet creating a circular current. If I had any more flow, it would uproot plants and I'd need Rainbow fish :) I wonder if too much flow could be contributing to a long Co2 dwell time? I try to keep the water surface dancing so it's not breaking the surface and so that I can see the plants through the water surface with a little distortion.
 

Zeus.

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If you're an over-the-top fanatic like me, using matter/anti-matter di-lithium power cells, it takes about 20 minutes
Or twin CO2 injection/solenoids and PLC, 500litres DC to light yellow 20mins was about the fastest I have managed. Did need a high injection rate all the same.
 

Zeus.

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If I had any more flow, it would uproot plants

Having used twin Maxspect Gyres it surprizing how much flow you can have and not unroot plants, fish seem to do fine also with high flow also, however non of my fish are over 3cm, biggest livestock in tank is the amanos, some fish would/would make high flow an issue IMO
 

Franks

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Cheers Zeus,

Some more background, my angels were hanging around the top of the water surface when pH was dropped a whole unit and my 4kDH DC was bright yellow. The pH pen is calibrated but that's not to say it's accurate. I dialled back the injection rate and will aim for a nice lime green DC. I'm not aiming for a 'ragged edge' approach to plant benefits but I do want to be growing advanced plants all the same. I'd imagine as long as my Co2 and ferts are consistent, then all will be well. Lighting is capable of anything and only running at 70% during its peak day period and this coincides with the sweet spot where the water is at its most Co2 saturated point.

I'll observe and make subtle changes but I don't think it's possible for me to gain quicker Co2 saturation of the water column without looking into a reactor.

Thanks guys
 

Zeus.

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4kDH DC was bright yellow.

That is best way of 'estimating' [CO2] is the DC colour change, a pH pen is useful for doing profile checking for stable pH on the day, but the pH reading is irrelevant in its magnitude, the pH pens change/direction is very useful and go off the DC.
If the DC colour change is same day after day at same time then same [CO2]
If the pH changes at the same time of day after day is it the GH, KH, or [CO2] thats changed ? many use AS which is an active component along with rocks with CaCO3.
If our tank have inert substrate and rock then pH can be trusted a little more, but the DC can be trusted
 

Franks

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Thanks again Zeus, I think I've dialled it in well now. Although bad news, Im suffering what I think is diatoms/dust algae on all leaves of the plants. I've added 4 Otto's as I've had these in the past and they were great at eating bits of algae but these guys seem disinterested and just stay on the redmoor!

Ammo 0
Nitrite 0
Nitrate 80-160ppm

Although that Nitrate seems high, I am dosing high macro and micros so this could be a contribution but I didn't want low nitrates while the plants are trying to establish. I've also observed the inlet and outlet pipework looks dusty too and the tubing is brand new.

So in order to defeat these diatoms, I'm thinking I should add another 50% water change per week but should I also reduce lighting intensity? Is this the right way to go?

Thanks
 

Zeus.

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I'm thinking I should add another 50% water change per week but should I also reduce lighting intensity? Is this the right way to go?
Don't panic ;)
IMO, Yes clean all glass and reduce intensity, cut down low light periods, any natural light you can block out also, a piece of carboard in front of tank can do the trick short term. A double 50% WC after cleaning glass will also help reduce the spores numbers in the water.
Dose ferts as normal
 

DaveWatkin

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Another trick I've found for speeding up diatom blooms is to clean the filter with every water change. Particularly pulling sponges and rinsing them thoroughly under the tap/shower and emptying any water out (if external filter). Bio media doesn't need rinsed every time but every now and then.

Diatoms are easily blown about the tank with flow and end up in the filter eventually makeing it back out into the tank. Rinsing the sponges helps get rid of any currently on there before they blow back out.

I might be wrong but it certainly seems to help me.
 

Franks

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Perfect. Thanks for the advice guys, I was hoping that since my canister and biomedia was super matured that I wouldn't suffer a new tank diatom bloom but seemingly this is not the case. There is brand new redmoor, dragon stone and clay substrate in the actual tank so I guess this is why diatom has exploded.

Of all the algaes, it's not too bad compared to BBA or Cyanobacteria (which actually isn't algae, but it's not wanted either way!) 🙂
 

jaypeecee

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I was hoping that since my canister and biomedia was super matured that I wouldn't suffer a new tank diatom bloom but seemingly this is not the case. There is brand new redmoor, dragon stone and clay substrate in the actual tank so I guess this is why diatom has exploded.
Hi @Franks

You may find it interesting to take a look at this other current thread:


JPC
 

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