# Cal Aqua double checker



## hotweldfire (26 Aug 2012)

Anyone used this? It's the one which has two bulbs, one with I assume a usual bromo blue/4dkh mix an th other with a "30ppm reference soluton". 

I have installed one 24hrs ago on my main tank and it is telling me I am putting in too much CO2. I.e. The test bulb is more yellow than the ref bulb. This is despite the fact that I'm injecting probably 15% less than I usually do. 

Are these things to be trusted? 

Sent from my MB860 using Tapatalk 2


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## Antipofish (26 Aug 2012)

I have one mate and it works fine.  Having said that, the indicator liquid you have may be at fault.  Is it new ?


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## Garuf (26 Aug 2012)

Nope. A lot of people run into trouble because they set their co2 to this arbitrary level of 30ppm when the truth of the matter is the tank might need 40ppm to be healthy and the fish might not notice at all.Drop checkers were always meant to be a guide, not a hard and fast.


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## andyh (27 Aug 2012)

i use one no probs


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## hotweldfire (27 Aug 2012)

Thanks all. Chris - it is new. Garuf - I might be misunderstanding but I thought the point of keeping it at 30ppm is to ensure there is adequate co2 for plants during the photoperiod. Surely the amount of co2 will depend not just on the injection rate but also on uptake rate (and off gassing etc).

Therefore doesn't the dropchecker basically tell you how much co2 is in the tank and available to the plants when subtracting what they're taking up? I.e. what's left (albeit with a one or two hour lag)? In other words it is not an objective measure but a relative one?

Therefore a mid green DC tells me that if I was injecting co2 into an empty bucket there would be 30ppm in there. But in my tank I'd likely have to increase the injection rate considerably to get the same colour. So it tells me that there is 30ppm _left in my tank after plant uptake_ and thus 30ppm available to plants. No?


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## ceg4048 (27 Aug 2012)

No.

You are putting too much faith in a test kit again. The DC only can tell you what's happening at one point in the tank, and only what it WAS a few hours ago. What the plants has access to actually has very little to do with the reading. The DC is just a guide. What Gareth is saying is that an indicated 30ppm may be less than what a particular group of plants need depending on lighting, distribution, nutrient levels, temperature and other factors. People get too hung up with numbers and that's why vendors are able to get away with selling us goofy products like this. _Who cares_ what the reference color is. Some tanks using low light, or having excellent distribution, or which are at low temperatures, or which have hardy, CO2 efficient plants can use less CO2, so a blue/green indication can be fine. Other tanks which are on the opposite end of the scale may need toxic levels of CO2 for the plants to thrive. Green doesn't mean anything, and neither does 30ppm.

When we are teaching people how to care for a CO2 injected tank we give these basic guidelines on how to use the DC because having something visual helps them to get the basics down pat.

Barr has measured the CO2 levels with a real CO2 meter and he discovered that the plant beds are often seeing only one tenth of the CO2 concentration level  as measured by the DC. This is due to the hydrodynamics occurring in the beds and on the surface of the plants. That's why is so difficult to compare tanks.

So don't get hung up of green or on reference numbers. Look at your plants, because they will never lie. People get so hypnotized that even when the tank is obviously low on CO2 they refuse to consider that fact simply because their DC is green.

Cheers,


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## nry (27 Aug 2012)

Which is why, along with ditching test kits years ago, I haven't ran a drop checker in ages...


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## Antipofish (27 Aug 2012)

I have not used one in a while because mine got dirty and I have been too lazy to clean it.  HOWEVER I do think they are a useful reference.  NOT so you can say "my DC is lime green so Im doing fine" because what Clive has said is totally right, BUT so I can say " oops, my DC is not doing what it normally does, perhaps something has changed in my tank that I need to address or I have inadvertently left the CO2 off or knocked the knob and changed the setting".  Thats where they are useful.


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## nry (27 Aug 2012)

Yeah, that I get


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## hotweldfire (27 Aug 2012)

OK, OK, I understand that 30ppm may not be enough in some tanks. And I understand that one should primarily make judgements on the basis of plant/fauna health/behaviour but that is exactly why I bought the thing. Prior to rescape my co2 levels were, as far as I could tell, toxic as my fish were gasping at the end of photoperiod and I was starting to lose some. At the same time I had melt all over the place and new growth with holes as well as plenty of hair algae. Now to me that screams co2 deficiency. And yet I was pumping in toxic levels of co2.

Let me be clear. I gradually built up to those levels giving the fish plenty of time to adapt. Their behaviour indicated to me that they were getting close to the ceiling of what they could withstand. At the same time I was dosing EI and had very good flow (eheim 2071 with a koralia 1600 on a 125l).

Hence the double DC. So sorry to be touchy but it winds me up when people say they're only a guide, or you should look at your plants. I've been looking at my plants and they've been melting whilst my fish have been gasping. 

I'm not an idiot. I know that the DC is a guide rather than an accurate measurement of the co2 at every point in the tank right through the photoperiod. I know it is not a lab grade co2 test. I said I regarded it as a relative test of co2, not an absolute one. 

However, if I look at the DC at the end of the photoperiod it is giving me an indication of how much co2 was in the tank an hour or two ago at which point the plants had been photosynthesising for some hours and at which point co2 had been injected into the tank for some hours. Having a reference colour which is indicative of 30ppm and _that does not change_ is priceless when you're starting to doubt your own eyes. Yes it is the level at a certain part of the tank and it is not strictly concurrent. But it is still useful information.

So, Clive, I think you're being rather harsh on the product. I'm also slightly offended (only slightly) that you'd think I'm stupid enough to rely on this thing to tell me whether my parameters are correct. It is one source of information amongst many. What I was asking is whether the reference solution, when compared to bromo blue/4dkh, is really indicative of 30ppm of co2 (in that bit of the tank at a historical time point etc). Which you haven't answered. Instead you've basically told me I'm a test kit slave. Again. Seriously mate, I understand why you're sensitive to that issue but can we get past it now?


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## Antipofish (27 Aug 2012)

Hey Saj, just to re iterate, I have the same DC with the same fluid products.  I found, when I used it (and as I have said, it got dirty and I was too lazy to clean it although I will be doing so and re installing it when the new tank is done the way I want it), anyway, WHEN I used it it worked fine.  I injected 1 to 2 bps and it showed me a dark green compared to the reference fluid, I upped the injection and the colour changed accordingly (with the appropriate time lapse) So I think its safe to say that as long as the fluid you have is not duff there should not be a problem.  What I WILL also say is that I am not convinced that the reference colour represents anything specific.  Does the literature say it is meant to be indicative of 30ppm (I dont know as I got mine second had).


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## Ady34 (27 Aug 2012)

Hi mate,
Both your fauna and your dc are telling you the same thing so id say your dc solution is indicative of high levels of c02 within your tank. I've always suffered a similar battle with being on the brink with c02 so the next scape Im simply going to reduce lighting intensity so I can run with a more comfortable c02 level for the fish and in doing so reduce the demand from the plants for toxic levels of c02   
Cheerio
Ady


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## hotweldfire (28 Aug 2012)

Thanks both. Chris, good point, I had simply assumed it was meant to be 30ppm because why would they set it otherwise? I'm pretty sure the documentation said it was 30 but will double check. 

Ady, I hear you but I already swapped my t6s for t8s, removed the reflectors and reduced photoperiod to 6 hrs. Still had same issue. I think I would have had to massively reduce the photoperiod to not be on a knife edge. What's interesting is that my other two tanks that run 24/7 co2 are doing much better and the fauna look much happier. I wonder if it's not the stress induced by big changes in co2 levels as much as overall co2 levels that's the problem for the fish.


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## Antipofish (28 Aug 2012)

Saj are all the plants you have in the tank concerned, notorious for being high demand CO2 users  ?  I guess a tank full of "fussy" plants compared to a tank full of anubias is likely to have quite a different requirement.  I know you know this already... you were the one who pointed it out to me several months ago   But I am interested to know if your plants are ALL high demanders ?


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## Iain Sutherland (28 Aug 2012)

hey saj, i'd agree that the DC is really only a good indicator of if something has changed and also to move around the tank to check for distribution( at the sides of the tank at least).   
I know you can grow plants from your other tanks mate but if you want my 2 bobs worth from what your saying i would say that the flow would be you culprit, you said you flow is good with what you have but is it getting all around the tank? Low light, 'toxic' co2 and melt can really only mean one of two things and as you EI then must to flow distribution. I really only just started to fully understand quite how easily effected flow is in the last few months.
I lost the best part of a whole mother plant of microsorum trident (6 plants at £11 each   )...  all due to one new anubia coffefolia leaf just in front of it that grew in a position that  disrupted the flow... snipped the anubia leaf and the trident has almost replaced all its leaves now.
I know i havent said anything new you didnt already know mate but sometimes our tanks scream at us yet we miss the obvious, its easy to become blinkered to something... 'it cant be that because i have 15x flow etc '   I got that t-shirt too!


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## Antipofish (28 Aug 2012)

The anubias leaf analogy that iain cited above is a great example of how the slightest thing affects the fluid dynamics withing a tank environment.  I remember someone else having a similar issue where a "bank" of small rocks were deflecting the CO2 upwards.  So where it was clear from video evidence presented that the CO2 was reaching substrate level, it was then flowing backwards into the tank along the substrate and missing the plants in the middle because of these bloody rocks !!!  

Saj, show us a pic of the tank you are talking about


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## geoffbark (28 Aug 2012)

my two pennies worth......... and i have learnt most of my stuff from reading this forum (and barr report ) 

I use a drop checker to tell me weather i have co2 in the tank or not ( kinda like on/off ). When it is blue i know something is wrong with co2 kit  and green/yellow all is good.

I use pH and KH tables to work out co2 ppm (if i want to really know, for wot reason i dont!)

Mainly i look at fish and plants.

Now distribution is key for me.

You need to distribute the ferts and co2 evenly around the tank ( not teaching people to suck eggs!    )at flow slow enough for the leaves to take the nutrients out and fast enough to ensure co2 is spreed all over tank.

I have a 125ltr jewel, i have an eheim pro 2 750l/hr and a tunze 1500l/hr, i was injecting more bubbles than you can count and needed very toxic levels for plants to look their best.

I have since taken out the tunze and i use the eheim pro to dissolve the co2 and my bubble rate is now 1 bubble per sec.

The plants are great the fish are happier and the drop checker goes green.

So to recap i believe that you can have too much flow.


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## GHNelson (28 Aug 2012)

Hi gang
I know for a fact that some fish do not like high levels of Co2...especially if they are enclosed in a smaller aquarium.
You will gas fish and shrimp quicker in a 20 litre aquarium than a 100 litre...that's why you need to be on your guard...when you pump Co2 into a small tank.
Lime Green is a no no for me if you have inhabitants.
I use a timer to switch on Co2 but its only for 30minutes...if i can keep the Co2 level around Green on a drop checker all through the 24 hour cycle.... i know i wont gas my inhabitants .....who cares about the plants growth as long as the plants are healthy...and you don't kill your occupants.
hoggie


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## Antipofish (28 Aug 2012)

hogan53 said:
			
		

> .
> Lime Green is a no no for me if you have inhabitants.
> hoggie




With all due respect hoggie, it is somewhat meaningless to say that mate. (No offence).  Just looking at CO2 levels in a tank and saying one level is acceptable and another is not depending on whether there are fish in it has no scientific basis at all.  There are many other factors involved, not least of which is the concentration of oxygen in the tank.  Tom Barr, who I am sure we would all concede to be one of the most successful aquascapers on here (as well as on his own forum) often has twice if not three times the "recommended" levels of CO2 in his tanks.  WITH FISH !  And he has no animal husbandry issues.  I am pretty sure from reading his posts that this is because he also has high levels of O2 to support the CO2 in there.

The comment "lime green is a no no if you have inhabitants" is the very reason why people should not look at drop checkers to be absolute (which, Saj, I know you do not).

I suspect, though I do not KNOW, that the number of fish and the volume of the tank and the CO2 uptake rate of the biomass is also relevant.  The fewer the fish, the more of the O2 is available to them, and similary the greater the volume the more O2 available. Along with, I would expect, the faster the biomass CO2 uptake rate.  

You might not have meant to come across so absolute Hoggie, but the one thing I have learned, is to shy away from using any kind of aquatic indicator to base decisions on. Whether its the colour of a drop checker or the levels that a "test kit" tells us. My DC (when I bothered to use it) was always lime green after getting my CO2 right, and I have not lost a single fish nor seen any signs of significant distress.


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## GHNelson (29 Aug 2012)

Hi Antipofish
This is a personal observation for me...and i don't think its meaningless basis.. i will not pump Co2 into a tank to achieve a .. Lime Green drop checker...for the sake of better plant growth....if you have certain  fish that get stressed with a higher Co2 concentration...are you going to continue pumping Co2 into a aquarium?
I have observed fish being stressed due to higher Co2 levels..... the checker is Lime green.
As you touched on all aquariums are unique...no two are the same....there is a whole load of factors that come into it.Lighting/O2/Water movement/Stocking levels etc...even the species of fish.
I bet you that members have gassed fish or shrimp trying to achieve a Lime Green Drop checker....be it through inexperience or trying to calculate how much the Co2 should be run for.
Even experienced aquarists have came unstuck.
I have never heard of anyone gassing their fish/shrimp when the Drop checker is Green have you :?: 
We all know a drop checker is not accurate when it comes to Co2 levels its a visual guide only in one area of the tank.
I have grown healthy plants without pumping vast amounts of Co2 into the aquarium..using one 24 watt T5 bulb...drop checker Green fish are happy what does that tell you.
If you pumped Co2 into a aquarium without a drop checker and your fish where at the top of the surface gasping for Oxygen..would that not influence you to cut back on the Co2..or would you put your plants first. :?: 
Its my personal choice i wasn't trying to ride rough shod over anyone.
And no this is not a exact Science...we will learn by our mistakes.  
Have a niceday  
hoggie


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## hinch (29 Aug 2012)

I've removed the drop checker from my tank and instead rely on the rummy nose tetra in there 

If his head loses the colouring CO2 is too high.  If its still nice and red and no pearling then its too low.  If its red and  there's plenty of pearling I class it spot on.

Seems to be working for me at least no algae and massive amounts of growth


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## Antipofish (29 Aug 2012)

hogan53 said:
			
		

> Hi Antipofish
> This is a personal observation for me...and i don't think its meaningless basis.. i will not pump Co2 into a tank to achieve a .. Lime Green drop checker...for the sake of better plant growth....if you have certain  fish that get stressed with a higher Co2 concentration...are you going to continue pumping Co2 into a aquarium?
> I have observed fish being stressed due to higher Co2 levels..... the checker is Lime green.
> As you touched on all aquariums are unique...no two are the same....there is a whole load of factors that come into it.Lighting/O2/Water movement/Stocking levels etc...even the species of fish.
> ...



You seem to have taken offence at my post, and that was not my intention.  But you have even agreed with me above by acknowledging that each tank is individual and that other factors come into play.. I quote "Lighting/O2/Water movement/Stocking levels etc...even the species of fish".  You did not say this in your original post you simply said that a lime green drop checker if you had fish in the tank was a no no.  That in itself, without the qualification that we have both commented on after your post now, is meaningless.  It would even mislead new aquarists to thinking that it was not correct or feasible to achieve a lime green colour if they had fish in the tank.  Again, this is completely incorrect and as you have rightly agreed, a completely tank specific matter.  Its best to avoid generalisations without clarity   

Have a nice day ? In this poxy weather ?     Some chance.


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## GHNelson (29 Aug 2012)

I havent taken offence  
You seem to think that i am forcing some sort of rhetoric..on the members here.
I quoted it was personal to me that i don't run a drop checker to Lime Green.
You quoted (It would even mislead new aquarists to thinking that it was not correct or feasible to achieve a lime green colour if they had fish in the tank)
Of course they can...but they better be wary.
Whats misleading about trying to advise them that they could end up gassing their inhabitants.
I'm gonna leave it at that  
hoggie


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## Antipofish (29 Aug 2012)

hogan53 said:
			
		

> I havent taken offence
> You seem to think that i am forcing some sort of rhetoric..on the members here.
> I quoted it was personal to me that i don't run a drop checker to Lime Green.
> You quoted (It would even mislead new aquarists to thinking that it was not correct or feasible to achieve a lime green colour if they had fish in the tank)
> ...



All good. Fish welfare, as relating to CO2 has always been a contentious issue, especially as there are so many other ways we can kill 'em.  CO2 is just one.  And I agree its one that should come with a warning.  But not one that simply says what you said.  But I accept that its your choice.  I prefer to take more factors into account.


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## GHNelson (1 Sep 2012)

Yea factors do still gas fish you know  
Ask the best of them on here...like a few moderators.
 
hoggie


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