Very shy cardinal tetras and water questions

Question

aqua   QUESTION: Hi , it's been a month that I am keeping 20 cardinal tetras on my 10g tank , but havent realize until recently , that most of the time the are at the back of the tank where is more planted , they don't "swim" much (they stay static in one place for minutes , they swim again "at the back", and again they are static in one place) sometimes I can see them chasing each other and little biting... is this normal ?

Whenever I give them food , they eat a lot though...but after that , they are most of the time at the back of the aquarium... they will come to the front sometimes ,but will spend more of the time behind... Also whenever I come near , they just go away :(

I also keep 4 panda corydoras,3 Otocinclus sp and 5 amano shrimp and a couple of snails (clithon sp) and they all seem to be happy...but I'm worry about the tetras.... are they stress ?? too much light ?? (I have a 55W on top and I was told that might be good to have some aquatic plants on top ) not much space ??  

They guy who sell me the aquarium told me that they can fit in the aquarium though....(but recently I think maybe is a small space as I have the tank very planted )

Equipment is good I guess (lights are on for 10 hrs , air pump is on for 4 hours at night , DIY CO2 running all day , water temperature at 26-28 degress )

Although , today "after" my water change I messure the levels of No3 and is around 75-80mg/l and NO2 is around 5mg/l , I hear this is not good ??
GH is 3-6dH (soft)  

PH levels are 6.5 , and I also got some brown algae in the front of the aquarium :(( (this is why I got the oto and the snails )

Please help !

ANSWER: Hi Miguel,
What a beautiful tank! However I can see some of the brown algae you are talking about. This algae is common in new aquariums and I feel it is a signal that something is out of balance in your tank. Or perhaps there are too many nutrients in your tank.

The cardinals behavior sounds pretty normal to me. But it does sounds like they are shy and not use to people yet. Cardinals are easily spooked little fish and they probably just need more time to get adjusted. It could help if you had some floating plants on the surface. When they are eating that is always a good sign.

*If your NO3 (Nitrate) is 75-80 mg/L that is -very- high and not healthy for fish. I would start doing daily 30% water changes to bring it down. Your nitrates should be 20 mg/l and ideally a -lot- lower. Perhaps this is why the brown algae is growing.

*The presence of NO2 (nitrites) is also a red flag. This is very risky for your fish. Your tank must not be established completely yet. Nitrites should always be ZERO.

The best thing I can recommend is to start doing the daily water changes until your tank's NO2 and NO3 are at safe ranges.

Best of luck and I hope this helps!!
Karen~

---------- FOLLOW-UP ----------

QUESTION: Thank you very much Karen...how long do you think it will take for NO2 and NO3 to be at a safe ranges ?

Also I have a question about DIY CO2 , Is one bottle of 2 litters enough for my tank ? I can see some plants/leaves turning brown and Im taking them off but I feel that DIY CO2 doesnt have too much power(i.e: whenever I make it , I need to shake it every 3-4 days , otherwise It wont have the same power like when the new bottle start ) Also the diffuser gets clogged a lot , do you have any recomendation for this ?
Currently I have put Flora dose from "Red sea" and also treating the plants with Brighty K from ADA (Is the only potasium I can get in japan) Is this enough ? Or do you recomend to put something else ?

Thank you very much
Miguel

Answer
Hi Miguel,
Something must be out of balance for your tank to be a month old and still have nitrite and high nitrate problems. Perhaps you have clogged substrate harboring waste and decomposing debris. I think water changes are the best thing here and try to make sure the gravel and filter is not clogged.  Most aquariums are fully established within 4-6 weeks but it all depends upon your individual setup and circumstances.

With DIY units you do have to shake the bottle every so often to get things going again. However, I'm not too sure about the clogging problem - what kind of difusser do you have? Most DIY systems will run the tubing into the power filter where it will dissolve it quite well...Airstones usually are said to not be very good at all.

Brown leaves on plants is probably normal unless it is in great quantity might signal excess phosphates in the water. This is a great website on diagnosing plant nutrient deficiencies-

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



Unfortunately I don't have too much knowledge on DIY CO2 but here is a detailed article that may help-
http://www.qsl.net/w2wdx/aquaria/diyco2.html

As far as the fertilizer questions, I think your plants will tell you more than I can recommend. If they seem to be doing poorly something must be in deficiency but you should be able to pinpoint what they are lacking with the website I listed.

I hope this helps and best of luck!!!
Karen~