# Drop Checker Permanently Green



## Chris Stokes (17 Oct 2017)

Evening all,

Anyone got any ideas why my drop checker stays green 24/7? CO2 (3bps and in-line diffused) comes on 4 hours before lights on and turns off 30 minutes before lights off. Really good surface agitation, with an eheim surface skimmer and an air pump running for 6 hours overnight. Also running Twinstar M5. 

With all of the above I’d expect the CO2 to gas off reasonably quickly, but seemingly it doesn’t. I’ve taken the drop checker off the tank and it returns blue.

Many thanks in advance.


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## MadMike (17 Oct 2017)

I been looking at mine recently and wondering the same thing. I put it down to the available co2 simply not being used. I'd love to know if it's something else though! 

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## Stuart_B (18 Oct 2017)

Chris Stokes said:


> Evening all,
> 
> Anyone got any ideas why my drop checker stays green 24/7? CO2 (3bps and in-line diffused) comes on 4 hours before lights on and turns off 30 minutes before lights off. Really good surface agitation, with an eheim surface skimmer and an air pump running for 6 hours overnight. Also running Twinstar M5.
> 
> ...


Is it not meant to be green all the time?


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## Zeus. (18 Oct 2017)

Think the slow change in the DC will be compounded by the slowly changing diffussion gradient as our tanks slowly degas. My tank has airstone on from lights off till CO2 on and the pH is still slowly climbing some 15hrs after lights off.


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## Puntius (18 Oct 2017)

Zeus. said:


> Think the slow change in the DC will be compounded by the slowly changing diffussion gradient as our tanks slowly degas. My tank has airstone on from lights off till CO2 on and the pH is still slowly climbing some 15hrs after lights off.
> 
> 
> Sent from Mountolympus via neural interface


My ph in tank around 20h30 is about 6.7 or 6.8 when my 30cm airstone comes on run by a nice big dual air pump. Around 06h15 in the morning by ph has climbed to 7.9 and a bit later back to the default at around 8.2

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## Zeus. (18 Oct 2017)

Puntius said:


> My ph in tank around 20h30 is about 6.7 or 6.8 when my 30cm airstone comes on run by a nice big dual air pump. Around 06h15 in the morning by ph has climbed to 7.9 and a bit later back to the default at around 8.2
> 
> Sent from my SM-G930F using Tapatalk


Relatively Similar pH drop/swing to my tank.
pH probes/pens are consitantly unreliable long term to any degree of accuracy. Hence the reason I've stopped using my pH controller during the photoperiod, having the CO2 injection rate change is just fluctuating [CO2].
But using a pH pen/probe short term is a great way to check for stable [CO2], having both the pen was the best buy IMO not much difference in price between DC and pH pen either.

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## Edvet (18 Oct 2017)

Have you got a pH measuring device? or can borrow one?
pH drop in relation to waterhardness gives best indication.


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## Nigel95 (18 Oct 2017)

Mine doesn't turn blue to. I just accepted it everything is growing fine.


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## Zeus. (18 Oct 2017)

Nigel95 said:


> Mine doesn't turn blue to. I just accepted it everything is growing fine.


At my level of understanding it doesn't matter if it goes blue. Having the extra CO2 avialible non photo period has no disadvantage except waste OFC. Extra gasous exchange during the non photo/CO2 period however keeps the [O2] at higher levels which is when the plants consume more, hence increasing gasous exchange during the period is one way of making sure demand for O2 is met.

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## Edvet (18 Oct 2017)

Zeus. said:


> extra CO2 avialible non photo period has no disadvantage except waste


Fish might not agree


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## Zeus. (18 Oct 2017)

Edvet said:


> Fish might not agree


Yep having the CO2 on in the non photoperiod is asking for trouble with livestock IMO also. 
esp if like myself your pH drop is over 1.0. As once the product of CO2 being produced by the plants isn't being used by the plants, the CO2 released by the plants plus the CO2 being injected could net an increase in the [CO2] which in turn could induce respiratory acidosis in the livestock that was close to their limit.
But if the livestock have survived the [CO2] I threw at them for six hours, does it matter if the [CO2] drops off slowly or fast? Just CO2 off at lights off at the very very latest ( my CO2 goes off one hour pre lights off, or should I say CO2 goes off 5hrs lights on).
After all we may increase surface aggitition at night which increases gasous exchange and our tanks degas their injected CO2, till in equilibrium with the local atmosphere. But that's a side effect of our aims not the target. We increase surface aggitition to keep [ O2] optimum at night period.
If our plants in our high tech tanks are using up to ten times the nutrients that's X10 the O2 being used at night in my books anyway.


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## kadoxu (18 Oct 2017)

I had this happen in my tanks where my drop checker didn't change from green, I just added an air pump that ran over night and after that, the drop checker was always blue in the morning.

Just a week or 2 after that, the Red Cherries started breeding (which never had happened to me in the previous 6 months)... interesting, right?!


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## AverageWhiteBloke (18 Oct 2017)

What you guys using for diffusion out of curiosity? I found when using reactors co2 was still diffusing well after it had been knocked off, before adding my surface skimmer I found my dc stayed green pretty much all the time, probably due to a thin layer on the surface. Now I use it my dc is always blue in the morning when co2 knocks off at 9pm. You also have to take into account that plants release co2 over night as well. 



Zeus. said:


> We increase surface aggitition to keep [ O2] optimum at night period.



Surface agitation is also important during lighting period, we can run quite high levels of co2 as long as there is plenty of 02. Problems arise when there is high co2 and low o2 regarding toxicity to fish. At night you have left over co2 from the injection, plants and fish producing co2 and every one of them consuming o2 including the filter so getting the co2 gassed off and increasing the o2 in the dark period reduces the risk through the night.


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## Zeus. (18 Oct 2017)

AverageWhiteBloke said:


> What you guys using for diffusion out of curiosity? I found when using reactors co2 was still diffusing well after it had been knocked off, before adding my surface skimmer I found my dc stayed green pretty much all the time, probably due to a thin layer on the surface. Now I use it my dc is always blue in the morning when co2 knocks off at 9pm. You also have to take into account that plants release co2 over night as well.
> 
> 
> 
> Surface agitation is also important during lighting period, we can run quite high levels of co2 as long as there is plenty of 02. Problems arise when there is high co2 and low o2 regarding toxicity to fish. At night you have left over co2 from the injection, plants and fish producing co2 and every one of them consuming o2 including the filter so getting the co2 gassed off and increasing the o2 in the dark period reduces the risk through the night.



Yep I used reactors which are feed by my Fluval FX6 which auto restarts every 12hours, I have this on a PLC so stops one hour before CO2 on. This stop in flow allows any trapped Gas in the reactors to get out, due to a fancy bit of plumbing. Because of the time of the stop the next autostop of the filter is five hours after lights off.

To you second point yes and no IMO. As long as the pH is dropping slow or fast it doesn't matter as long as dropping and doesn't get near the toxic levels. But the main aim of running an airpump at night as an easy cheap way to increase surface aggitition above day time levels to help maintain healthy O2 levels- plus all the extras like reduced surface scrum.
So why not have the extra surface aggitition all non photo/CO2 period. T. Amano. had his tanks setup for all night time increase surface aggitition by just moving the lily pipe return. The O2 demand of the tank will be relatively constant all night so keeping surface aggitition extra high all night is surly a win/win


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## AverageWhiteBloke (18 Oct 2017)

Zeus. said:


> Yep I used reactors which are feed by my Fluval FX6 which auto restarts every 12hours, I have this on a PLC so stops one hour before CO2 on. This stop in flow allows any trapped Gas in the reactors to get out, due to a fancy bit of plumbing. Because of the time of the stop the next autostop of the filter is five hours after lights off.
> 
> To you second point yes and no IMO. As long as the pH is dropping slow or fast it doesn't matter as long as dropping and doesn't get near the toxic levels. But the main aim of running an airpump at night as an easy cheap way to increase surface aggitition above day time levels to help maintain healthy O2 levels- plus all the extras like reduced surface scrum.
> So why not have the extra surface aggitition all non photo/CO2 period. T. Amano. had his tanks setup for all night time increase surface aggitition by just moving the lily pipe return. The O2 demand of the tank will be relatively constant all night so keeping surface aggitition extra high all night is surly a win/win


Yeah that's what I was saying, keeping the extra surface agitation going at all times. Obviously having it running during the light period is going to waste even more gas than we waste already. Can't really comment on the o2 use during lights out as I've never tested for o2 levels but I can imagine that you have a period of producing oxygen and then a period where everything is consuming oxygen and none being created that levels will be vastly different in the two phases. Hopefully enough had been produced during lighting to cover the night. At what rate it gets consumed I don't know.

Coming back to reactors, there's been an on going debate in these forums for many years on the the best way to diffuse reactors or all the various atomiser type products. Some say that although atomisers are wasteful of gas they benefit the plants because small bubbles stick to the leaves and get readily absorbed whereas reactors dissolve all of the gas into solution. With atomisers the bubbles are up and out the system hopefully with some of it clinging to leaves. There's not many bubbles fully dissolve before reaching the surface. The debate is whether co2 enriched water is easier for the plants to absorb co2 than pure co2 bubbles on the leaves.

In the case of reactors, I know when I used one even after the visible co2 within the reactor had gone co2 seemed to stay in solution well after injection.  I can only guess that's because it's dissolved as opposed to still being a bubble so with the co2 being produced at night from plants and fish and the co2 being in solution the DC won't have much time to change before the process starts again.

I liked my reactor for water clarity but I was getting to the point where my setup was starting to look like an intensive care bed. Just too much equipment to be dealing with for me. Since switching to inline atomisers it gasses off pretty quick. Because of all the mist some does get trapped in the canister which it does burp off now and again so I guess I also have co2 sitting in there still diffusing over night as well. Clearly not enough to keep the DC Green until morning though. 

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