can i use co2

[troy]

Hi

I have been raising young discus in a planted tank for 7months now , everything has gone well with the growth of the fish . but the plants are not growing so well as their growth is too slow. So i have been thinking about using co2 to help the plants . I have read that co2 will increase my PH, but my ph is already 7.6 , would this be too high to use co2 ?
How much does co2 generally increase the ph by?

Troy

[ronrca]

Actually, your ph will decrease or go down instead of up. My ph is also 7.6 without C02 injection and at a bubble rate of 1-2 per second, my ph drops to around 7.0-7.2!

Yes, C02 is beneficial in plant growth but it is also dependant on your lighting intensity and fertilization.

[Paulio]

Excellent reply Ron. One other thing to be very aware of when injecting co2 is the carbonate (kh) level of your tank. If it is too low you can cause a pH crash rather quickly.

Paul

[angel12]

There is a direct link between KH/Co2/and Ph from the Ph you say you have 7.6 looks like you have enough Kh in your tank water to be able to add CO2 in order to reduce your Ph through the production of Carbonic acid...
However it might be an idea to get a Kh testing kit to confirm what the Kh of your water is .....

Then take a look at this page for the relationship between Co2 and Kh/Ph

http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm

:)

[Emanuel]

Could you provide us with your tank parameters? Things like size of tank and fish population, water temperature, light source and intensity, amount and frequency of fertilization, water change frequency and types of plants you have. I would invest in $20 master test kit so you can closely monitor your ammonia, nitrites, KH, pH, etc. Finally, a picture would be very helpful as well. :)

[troy]

Hi all Thanks for your replies.

My tank parameters that i know of at the moment are GH & KH are both 5
Water temp about 29, 330L , water change of 40% daily , 6 discus , 2 bristle nose, 2 corys, 1 clown loach. At the moment i am using 2 triton tubes 40 watts , i am adding another soon . I use a little fertilizer in the gravel every now and then but some of it would be sucked up with gravel cleaning.
I did not know ph will go down rather than up using co2, thats good.
Unable to get pictures at the moment , maybe in 1 months time.

Troy

[Emanuel]

Thanks, Troy. You still didn't mention what plants you have but the rest was pretty descriptive. :) First, at such high temp a lot of plants do not grow optimally. Second, your light is low, only 1W/g if my calculation is correct. Third, you will need liquid fertilizer such as Seachem Flourish or Tropica Mastergrow and perhaps extra potassium. The 40% water changes may not leave enough nitrates for the plants but you'll need a test kit to verify that. Substrate fertilizer is good for swords and other plants but some plants use nutrients from the water column. Forth, do all plants exhibit low growth, or do some look stunted or the new leaves look deformed? If so, the clown loach may be to blame. I've had one that destroyed alot of my plants (including swords and anubias) by nibbling at night at the apical meristem (emerging leaves area) of plants. Finally, from what you described, you don't need CO2. Good luck!

[ChloroPhil]

Take a look at the "Answer to some Algae Questions" post I wrote at the top of the forum. It's actually more of a nutrient supplimentation guide and should help out a lot.

[knobby]

I am with emanuel on this one. With your 40% daily water changes there simply isn't enuff nutrients left for the plants to grow well. In your efforts to maintain clean water for your discus you are starving the plants....

I dont know how old your dicus are now...you said youve been raising them for 7 months so we know they are atleast that old. If they were atleast a couple months old when you got them they should be nearing maturity soon.

I will agree that LOTSA food and LOTSA water changes are the ideal way to grow up young discus. But IMO mature discus simply do not need anywhere near 40% daily WCs....especially in a well planted tank where the plants are consuming the remains of the biological processes as their food source. If you feel that your discus have grown as much as they're going to I think you can drastically reduce your WCs...probly even down to 10% a couple times a week.

Only real way to tell is through frequent testing...I am no plant expert but if you keep an eye on your nitrates/phosphates you should be able to tell if you're changing enuff water...

[ChloroPhil]

If you're willing to make the $$ investment in chemicals most plants don't mind daily water changes. It's just a lot of money in chemicals to be throwing down the drain.

I was doing a daily substrate skimming and algae removal and ended up taking out only 5-10g/day in a 90g. My plants didn't mind at all and the volume of chemicals lost was very inexpensive to replace.

[troy]

Thanks all , very helpful here

I am now thinking to move these younger fish into my smaller tank to continuing their growth and putting my full grown discus in my planted tank and grow good plants for a change. The only problem with the full grown discus they are in pairs and may fight too much , if so i may have to split them up and see if that works.

I have some questions for you guys, what would be the best temp for the plants and the discus?
should aeration be used with plants?
Can normal trace nutrient plant food from the garden shop be used or is the stuff from the fish shop be used?
Would the bristle nose be the one putting holes in my plants?

Hope you don't mind all the questions.

Troy

[ChloroPhil]

What would be the best temp for the plants and the discus?
-82-84 *F

Should aeration be used with plants?
-Not if you're injecting CO2 gas. Seachem Excel or Kent Grow won't be affected.

Can normal trace nutrient plant food from the garden shop be used or is the stuff from the fish shop be used?
-If it's not specifically for Aquarium use you should use Hydroponic or Food grade chemicals. Stay away from Miracle-Gro type fertilizers.

Would the bristle nose be the one putting holes in my plants?
Quite likely. It could also be nutrient deficiency or a new plant adapting to underwater life as well. What do the holes look like?

[troy]

Hi

The holes in the plant leaves look like large hole or chunks missing from the plants leaves, there are damaged eges of the leaves, looks like chunks missing there too, from what you guys were telling me the edges of plants could be damaged by the loach.
There are also a couple of leaves with lots of tiny holes.
How do others get on with bristle nose in there tank.

[ChloroPhil]

I would say that the larger holes have been caused by the bristlenose. They have a tendancy to rasp on sturdy leaves that can support them. Anubias and sword species are especially vulnerable.

The small holes may be from too low Potassium or your Loaches...maybe even both.

[ronrca]

I would also like to underline the importance of ferts! As it is, I have been 'experimenting' with my planted tank these last 4-5 months. I must say that it has ended in near disater. The first experiment was to change the lighting duration by splitting up the duration with a break in between. Lights on 5:30am-10:30am, off 10:30am-4pm, on 4pm-10pm. Plants did not like it, algae loved it! I did this for 4 months!

Then I stopped adding ferts daily and only weekly! Not enough! Now Im starting to add every second day with lighting duration on from 12pm to 10pm!

The results! From the first test, the plants grew but slowly. Algae soon took over. I cleaned weekly with 50% weekly!

The second test, algae growth slowed but still grew, plants really suffered and almost died.

Just thought Id share this and emphasis the importance of fertilization (and also lighting duration). ;) O yeah! I also use C02 injection!

[troy]

Good to know that ,thanks ronrca.

I will have to see if it would solve my algae problem so i can do away with the plecs that are damaging my plants.

[Keith.L]

Ron et al,

I have a newbie question that is not related to plant growth.

If the addition of CO2 lowers pH value slightly, what if I increase airflow to the tank by additional airpumps and/or airstones - will this raise the pH slightly?

I am just wondering how this will affect the fish. Thanks in advance.
-Keith 030814

[ChloroPhil]

Keith,

Adding airstones will remove any injected CO2 from your system. However, by adding CO2 your plants will oxygenate the water, more than compensating for any lack thereof. Also, if the KH is sufficient (3-4 degrees) any pH swings will be very mild and gradual. ~.1-.2 over a 12 hour period. Nothing your fish can't handle.

Best,
Phil

[ronrca]

what if I increase airflow to the tank by additional airpumps and/or airstones - will this raise the pH slightly?
Depends on how much C02 you have in the water to begin with. When I age (heated and aerated) my tap water which has a ph of 7.0 initially, the ph rises to 7.8! The ph will not go any higher than that because it has no more C02 and the ph is now dependant on the water chemistry like kh/gh!

In a planted tank, if you use aeration you will be defeating the purpose of C02 injection or C02 produced by the fish. Therefore the plants will not be able to 'breath' during the day. However, some plants are incredible. Some plants will actually 'extract' the carbon in the water (carbonate hardness - kh) if no C02 is available.

The relationship between C02 and ph swing is dependant on the kh and also the injection rate (bubbles/second).

[Keith.L]

Hi guys, thanks for the feedback!

I know very little about water chemisty, or for that matter the correlations between kH and the rest (CO2, O2, pH, etc.). It's all new and interesting to me. Thanks again for the insightful explaination!

As far as my tank goes, actually I don't have CO2 supply to my tank - it's just a simple BB for 4 discus with a couple of potted plant tossed in for them to hide.

It's just something that I was curious about. Thanks again.

-Keith 030815