CO2 poisoning my discus - newbie needs help!

[ceveji]

Hi everyone,

I have had a 60g discus tank for about 6 months now and until a week ago, when I began adding CO2, everything was nifty. I'm embarrassed to admit that, in the last two days, however, my beginner status is becoming dangerous to my fish! In this spirit, I would REALLY appreciate some pointers.

So my tank is moderately planted, has a pH of 6.8-7, and has a KH of 2.5. According to the CO2/pH chart, this means I'd be injecting around 12-15ppm. Right? So I began injecting (about 1-2 bubbles per second). I have a pH controller, which I set at 6.8. This means that sometimes the CO2 will be injected during the night.

The issue though has been in the evenings. For the second day in a row - and I hate to admit this, because I really care about my fish - I've come home from a dinner out to find my fish "resting" very palely on the substrate. Terrified, I changed about 60% of the water (this was last night). Today, I turned the bubble count (which had been at about 2 bubbles per second down to 1 bubble per second down to less than a 1 bubble per second. I turned the CO2 on around noon. We returned from dinner tonight at 11:30 pm to find the CO2 still on and the fish - again!!!! :scared: - sick with CO2 poisoning. Second massive water change.

What am I doing wrong? Is any CO2 too much for discus? Who does CO2 & discus and can help me figure this out and stop almost killing my dear fish? Can anyone tell me if fish incur permanent damage from two near-death experiences of this sort?

Thank you... C

[pcsb23]

This is why I tell newcomers to discus and planted tanks to learn them separately, and then put them together once they understand what they are doing, both take skill and high tech tanks take the greater skill.

mmm, first off discus will be pale at night - it is normal if the lights are out. However if they are laying flat then that is indicative of CO2 poisoning. However 2 bubbles per minute is not a lot of CO2.

So lets get some basics sorted out. The first thing to realise is that plants give off CO2 at night, they use CO2 during daylight (or lights on). Many things can affect pH which can mean under or over dosing CO2, the charts are ok but only ok, at giving an estimation.

Using a pH controller will result in issues, it only cares about pH. By all means us it to monitor pH, but don't use it to control CO2. One of the biggest causes, after light, of algae is fluctuation CO2 levels. A pH controller will switch the CO2 on and off all the time so the actual levels of CO2 fluctuate - and this can be exacerbated by low flow as the only time the controller knows if it is to switch on/off is when the measured value at the probe varies. With low flow this will be feast or famine. So we get large fluctuation in CO2. So by spending money on a device to control pH (and therefore CO2) what we have in fact done is lose total control and caused problems, both for the fish and the plants.

The hard-core planted geeks will tell you that you must have 30ppm CO2, all I can say is that is BS. What you need is constant levels of CO2, the fish have to come first (in our case). So a simple, and inexpensive, 24 hour timer is all we need and a solenoid for the CO2 (which you should already have). Set the timer to switch the CO2 on 2 hours before lights on and switch off 2 hours before lights off. Decide on how many bubbles per minute and leave it there. Review after a week, but don't change it daily.

Make sure you have surface agitation, be that from the outflow from the filter or a small power head aimed towards the surface, it needs to ripple. You must ensure good gas exchange, note I said MUST, not should.

You will note that you will not be running CO2 overnight.

We can't talk about CO2 and not talk about light they are related closely. The amount of CO2 used is driven by the amount and quality (read PAR at the leaves for this) of the light. Make sure that the lighting is adequate but NOT too much, this will invite algae and will start to compromise water quality. Start with 7 to 8 hours solid duration and adjust from there, be guided by the plants and any algae. If algae start to show, reduce your lighting intensity and/or duration.

It is also necessary to ensure that the plants have enough ferts, particularly NPK and trace.

As I said planted tanks take more skill and knowledge particularly high tech (injected CO2 = high tech) :)

[rvales]

Paul,
You are very knowledgeable when it comes to high tech tanks. Can you please tell me what brand names I should purchase for the fertilizers (NPK and trace).

[pcsb23]

Paul,
You are very knowledgeable when it comes to high tech tanks. Can you please tell me what brand names I should purchase for the fertilizers (NPK and trace).I use dry salts and buy them in (relative) bulk, this is the site I use but it is UK based, I'm certain there will be equivalent sites where you are. http://www.aquariumplantfood.co.uk/ All I use is KNO3, KH2PO4, MgSO4 and their chelated trace mix. My tank uses pressurised CO2 and I supplement that with EasyCarbo too.

[Larry Bugg]

Two good places to get your dry ferts.

http://www.aquariumfertilizer.com/index.asp?Option1=cats&Edit=2&EditU=1&Regit=2

http://greenleafaquariums.com/aquarium-fertilizer.html

[du3ce]

U need to ease your fish to co2 start off low and then build up their tolerance

[ceveji]

Dear all, thanks for your responses. I just realized I wrote "bubbles per minute" but I meant bubbles per SECOND! Paul, your post remains incredibly helpful. Thanks and I will stop depending on that dastardly pH controller!

What can I use to create surface aeration for the nighttime? A tank fan-type device?


My light is one of those Marineland LED aquatic plant lights (36"/1 meter). Reading from the box, it says the PAR at 12" is between 172-30 (172 if directly under the middle, I guess 30 if at the edges?) and at 24" the range is 83-27 PAR. Is that too much/little light?

[DC Discus]

Paul has very good advice! especially

"Make sure you have surface agitation, be that from the outflow from the filter or a small power head aimed towards the surface, it needs to ripple. You must ensure good gas exchange, note I said MUST, not should"

If your using a canister type filter have the spray bar agitating the surface. Discus consume a lot of oxygen and it sounds like you're running into whats called hypoxia (lack of oxygen). Remember warmer water (80F) has considerably less O2 then cooler water. So if your plants are using more when the lights are off it due to better growing conditions (CO2 availability), doesn't leave a lot of O2 for the fish. You'd be surprised too that the bacteria in your filter use near the same amount of oxygen as the fish.

Good luck!
Cheers,
DC

[pcsb23]

Dear all, thanks for your responses. I just realized I wrote "bubbles per minute" but I meant bubbles per SECOND! Paul, your post remains incredibly helpful. Thanks and I will stop depending on that dastardly pH controller!

What can I use to create surface aeration for the nighttime? A tank fan-type device?


My light is one of those Marineland LED aquatic plant lights (36"/1 meter). Reading from the box, it says the PAR at 12" is between 172-30 (172 if directly under the middle, I guess 30 if at the edges?) and at 24" the range is 83-27 PAR. Is that too much/little light?
Wondered if you meant seconds that's why I queried it. The PAR levels are quite high @ 24", puts it well into high light, I'd be tempted to find a way to dim I a little (ND gel - photographic/film paper reduces light throughput, comes in a variety of densities).

The surface needs to be agitated all day, not just at night. Have the filter output ripple the surface usually works.

[dirtyplants]

Your co2 should be on a timer 1 hour after lights are on and one hour before light go off if your plants are well established. Two if the plants are not established with a good long root system. Agitation on the surface at night is a must especially if you have large fish. You should get away with three bubbles per second. Plants use oxygen at night they do not use CO2 at night so placing a timer with your solenoid valve to turn off your co2 will not result in a major rise/drop in ph at night. So your night time issue is lower oxygen / redox levels, ( if you actually have a large amount of plants) your ph should stay fairly stable because your plants are not using up the co2. If you have a large amount of agitation during the night this will reduce the co2 and your ph will rise or drop, depending on the mineral/ hardness of the water.) IF you lack minerals your ph may drop. A certain amount of calcium hardness is necessary if you wish to keep the ph stable. So gentle agitation is suggested. Surface agitation is important for gas exchange both during the day and the night. Unless your plants are well established and the nutrients levels have been mineralized out I would not ad ferts. I think it has been suggested before to cut out the co2 until you stabilize your tank which includes your co2. If you are not the same person then I will suggest to you to first keep a stable tank, addition of co2 and fish require a lot of monitoring and knowledge of the plants nourishment needs/requirements, along with knowledge of water conditions. I suggest you drop the co2 read up on how to set up your system with large fish and plants, drop the ferts until you know which plants really need ferts and how often. The Planted Tank site is a good resource for establishing a planted tank, discus on the other hand require compromise, and smart discus people with planted tanks stay with certain type of plants which work well with discus and discus water requirements.

[rvales]

Thank you Paul and Larry.

[ceveji]

Wonderfully helpful responses Paul & Larry - I echo the thanks! I currently have an aquaclear "waterfall"-type filter. Any recommendations of canister filters in which to invest? I bought a timer today so I will set it as you advised, Dirtyplants! Paul, as for having the filter output tube ripple the surface day & night, how do I position it? Thanks again... C

[RodneyL001]

I hope, you get it resolved, I love plants too, but decided to go with a low tech setup while I improve my discus skill set. No CO2 for me, except the liquid kind, I'm sure it is not as good, but my plants look healthy, and are slowly growing. Maybe next summer, if my wife gives me the ok, I might try the CO2 and ferts in the substrate, I will start out with some less expensive fish in that tank, guppies, gourami's and the like. If my wife ever found out how much I spent on having my 4 discus shipped from Chicago discus it wouldn't be pretty.

[pcsb23]

Wonderfully helpful responses Paul & Larry - I echo the thanks! I currently have an aquaclear "waterfall"-type filter. Any recommendations of canister filters in which to invest? I bought a timer today so I will set it as you advised, Dirtyplants! Paul, as for having the filter output tube ripple the surface day & night, how do I position it? Thanks again... CCanisters come in all shapes and sizes, I'm sort of stuck in the past with these and tend to stick to eheim 2217's and the like. Simple, efficient and bullet proof. Lots like the FX5 & 6 by fluval. As for the timer, the CO2 needs to be on at least an hour BEFORE the lights go on, not an hour after as Coree suggests, plants (and algae) utilise light immediately so need max CO2 at lights on, it tails off later in the day. As long as you are at or near max CO2 at lights on the plants will respond well and the algae won't - provided there isn't too much light and all else equal.