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How many BPM of CO2 in 30ltr shrimp tank

Flyfisher

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21 Jul 2012
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13
Hi all,

At the start of the year I got rid of my RIO 180 and downscaled to a 30ltr (approx. 25 ltr of water) Aquael shrimp set smart LED tank, keeping all 6 of my amano shrimp from the old tank.
I decided in the summer to install a new Dennerle CO2 system, as I ran one for a long time on my old tank and never had any problems.

I now have a Dennerle Regulator, night time cut off valve on a timer and mini Drop Checker, with a JBL Bubble counter/check valve and a twinstar mini diffuser. The CO2 is on a timer and comes on 2 hours before lights on at 13.00 and turns off at 7.30, 1.5 hours before lights out. Substrate is JBL Manado with no soil, but plenty of plant capsules inserted into the substrate.
Tropica liquid fert (non-Co2) is added every 10 days when i do a 30-40% water change. I do have some of the liquid fert for CO2 tanks but haven't used it yet as I am wary of it causing extra algae. I have a cheap Ikea LED lamp that I have added to the Aquarium that I sometimes turn on if I feel the rear plant growth is causing shading for some of the plants at the front. The main light is the LED that came with the tank set up, but I swapped out the set filter for a Dennerle mini one with a spray bar

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The problem is that no matter how much CO2 I have added, the drop checker always is a dark green colour. Also I have found that the Bacopa and tiny crypto plants that i have in the foreground are barely growing, though I appreciate that they are slower growing plants. There are plenty of plant food tabs stuck around the roots of these plants.

I have already tried 2 other types of drop checker and they all showed the same dark colour colour, so the problem isn't with the drop checker.

The most CO2 I have had going into the tank was 1 bubble every 6 seconds but I have dialed this back to 1 bubble every 12 seconds now after the 6 Galaxy Rasboras i bought all died, leaving just 1 offspring. I assumed that they died from too much CO2, or that the CO2 levels didn't help, though the tank was about 4 months old when I bought them. My amano shrimp all seem happy and they must be getting on for at least 4 years or more. There are no other shrimp or fish in the tank.

I bought a API 5 in 1 test kit and the results on conditioned tap water before it was added to the tank were: pH = 7, KH = 60 , GH = 180, NO3 = 0 and NO2 = 0. Temp is 24 degrees C. I ran the figures through some online calculators and they were saying that I should be putting in about 1 bubble every 20 seconds (3 per min) assuming I put in the correct figures. I have searched on this forum and elsewhere for posts that may help but to no avail. I don't want to kill off my amanos but just feel that I am not getting the best from the CO2 system. One other note is that I am using a spare old JBL disposable CO2 tank that was left over from when I last used Co2 about 3 or 4 years ago. It was full and never opened. I assume this wouldn't be an issue.

Could anyone please suggest what they think the BPM for the bubble counter should be for this tank? Any other useful tips also appreciated.

Thanks

Alan
 
Last edited:

Andy Pierce

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27 Nov 2020
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Cambridge, UK
If the solution in your drop checker didn't ever turn yellow, then excess CO2 is not why your rasboras died - must be something else. There is no standard sized bubble because different types of bubble counters make different sized bubbles and there's probably a dependence on the solution in the counter (I use glycerin), but that being said, in my 40 L tank I find 2 bubbles per second (120 per minute) is about right so 1 bubble every 6 seconds is not going to be enough, which is also why you're not able to shift the colour of your drop checker. If your bubble counter gets to be straw-yellow in colour and your fish are looking distressed, then you've gone too high with the CO2, otherwise, you haven't. :)
 
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South Carolina
I’m honestly surprised you even got your drop checker solution to change with that injection rate. I would increase to at least 1 bubble a second and see what happens. As the previous poster noted your raspbora definitely didn’t die from CO2 related issues. Even more so if you’re Amano are still kicking, they would go before the fish. You more than likely got a bad batch or something was off in the tank.
 

Flyfisher

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21 Jul 2012
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Thank you for the swift and informed replies. Those make total sense. I am just being overly cautious for the sake of the amanos.

The Galaxy rasboras were very timid and were so fussy they were almost impossible to feed. I tried 3 types of dried food and some frozen daphnia, but most of them just kept spitting out the food. Their deaths may have coincided with swapping over the filters as well but i made sure I had plenty of the old media in the new one.

I will bump up the Bubbles to 1 per second and see what happens, though personally i thought at 6 secs the water looked like a bottle of sprite.

I will let you know what happens

Cheers

Alan
 

dgilbert2

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30 Nov 2020
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Observation / question from my experience. The dropper checker is sitting at quite an angle, so the water surface within it is reduced. Also, there looks to be quite a lot more test solution in it than mine. Could these be a factors?

In my case, I now only put 7 drops into the DC and its response time is much improved. May also be worth checking PH at solenoid on and again when turns off to give you a second CO2 levels indication?
 

Flyfisher

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Thanks for the input. I hadn’t noticed that the drop checker was at a wonky angle so I have straightened it up.
That’s a good idea about checking the ph Levels before and after co2 goes in as well. I will try to do that tomorrow. I will also reduce the amount of drop checker solution when I next replace it
Thanks again
Alan
 

Flyfisher

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Just a bit of an up date. Today I got the bubble count up to I bubble every 2 secs and the drop checker is a medium green colour rather than the previous dark green colour. I will try try to up the C02 a tiny bit more tomorrow to get it to a nice light green colour. PH this morning before co2 on was 7 and then approx 6.75 at lights out. According the chart I have from Dennerle I need the pH to be around 6.5 to have the optimum amount of Co2 in the water.
 

dcurzon

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your 'lights out' is about 1.5hrs after co2 switches off, so probably not an ideal measurement.
try if you're able to:
if you're co2 on at 13:00/lights 15:00, try getting a bunch of ph tests to cover the day, pre and post co2/lights, for example:

12:00 ph CO2 off/Lights off
13:00 ph CO2 on/Lights off
14:00 ph CO2 on/Lights off
15:00 ph CO2 on/Lights on
16:00 ph CO2 on/Lights on
17:00 ph CO2 on/Lights on
18:00 ph CO2 on/Lights on
19:00 ph CO2 on/Lights on
20:00 ph CO2 off/Lights on
21:00 ph CO2 off/Lights on
22:00 ph CO2 off/Lights off
23:00 ph CO2 off/Lights off

The locals call this a PH profile, and whilst im definitely no expert on it, it should give an understanding of the pattern of the ph drop and from there, determine if more or less co2 is needed, or if a shift in timings is needed.
 

dino21

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Hi,

The drop checker fluid is quiet slow at reacting to changes in the water as there is an air inteface between the two, could be up to a hour delay.
As @dcurzon mentions, much better to use your standard API ph tests though out these set up days so you can better adjust your bubble rate.

For now suggest you aim for a stable Ph 7.0 and ensure you can maintain that for several days, and observe your plants and livestock, before attempting to go down lower.
 

jaypeecee

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Bracknell
Hi @Flyfisher

I'm wondering if the CO2 being injected isn't diffusing into the water properly. Which diffuser are you using? Are all the CO2 bubbles just quickly rising to the water surface and thus being lost? It looks as if that may be happening judging by your photo. Do the bubbles look like a fine mist? It is also very important to have some water flow in the tank to enable the CO2 to disperse and mix with the water. In short, it should be possible to see fine CO2 bubbles everywhere in the tank. BTW, what filtration system are you using? This is important as it provides the all-important water flow. A good indicator of flow is when the plants gently sway from side to side. And, finally, is the water surface being agitated a lot? If so, this will contribute to the loss of CO2 from the water.

Just a few things worth checking.

JPC
 

Flyfisher

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Hi all,

Thanks again for the replies. I will maybe try to do a pH profile soon but the API only shows increments of 0.5 e.g. 6.0, 6.5, 7.0.. It is currently sitting at about about 1 BPS after another fine tune yesterday. Just to clarify my photoperiod is 8 hours (13.00 - 21.00) with CO2 on at 11.00 and off at 19.30.

Jaypeecee - yes, I had wondered about my filter. It is a Dennerle nano EckFilter - quoted at 150L/h. I guess you would probably want it about 300lph for a 25-30L planted tank. I have the spraybar sitting at the back of the tank about 1 inch below the surface pointing forward with only a slight bit of surface agitation. I had wondered that the flow wasn't strong enough as there maybe isn't enough movement.

The diffuser is a twinstar C02 diffuser - small Twinstar Diffusor CO2 - Small (aquariumgardens.co.uk) I think it is working ok.

One final note is that I would swear the Bacopa is showing new signs of growth in just the couple of days I have upped the CO2.

Alan
 

Flyfisher

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Another update: I did a water change/ clean today.
I also took off the spray bar and diverted the flow of the filter at the stream of co2 bubbles to give better circulation. I have a spare diffuser for when the other one needs cleaning so swapped it in, as well as changing the drop checker solution. The result was that the circulation was greatly improved and the bubbles were a lot finer. All parts of the tank were full of tiny bubbles of co2, which is the general idea I guess. Unfortunately this lead to the drop checker very quickly turning yellow so I have had to dial back the amount of Co2 and will have to try and get it stabilised at a nice light green colour over the next few days. At least I know now that the circulation wasn’t good enough.
 

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