I took Tom's advice and bought 4 domestic bred discus for my 58g rather than some wild fish. I added them to the tank and they did fine for a few hours, then turned dark and I noticed their respiration was a lot higher than the other fish. I remembered a post where someone, possibly Tom, said discus turn black when they don't get enough oxygen. So, I pointed the Rio 50 power head I have in the tank to the surface and added an airstone in the flow. The fish lightened up and started eating.

Problem is, now the Ph rocketed from 6.2 or so to 7.4. I'm going to start trying to balance things out, but I would love to get some advice on this. I think part of the problem is that I use a canister filter on the tank (Eheim 2026) and they have a tendency to reduce dissolved oxygen.

Any ideas on getting the oxygen level up w/o depleting the CO2?

thanks for any help,

-Russ

Add another canister filter.
Then add more surface movement than what you had, a slight rippling is good.

Now add more CO2.

You will lose some CO2 this way, but it's easy to add more.
Larger fish require more/higher O2.

Good plant growth will help.
Do not add CO2 at night.

Do this slowly, do not try and wing it and add lot so of CO2 or then none at all, slowly raise it up and note fish health/color.

I never had these issues, I've seen them in other folk's tanks though........
Once they start eating and coming out more, then the CO2 can be upped some also.

Just do not push too fast.

Regards,
Tom Barr

Tom,

In regard to adding another canister filter - are you saying that the one Eheim is not enough for this bio load/tank size or adding one as a way of adding agitation? If it is that I need more filtration, would one larger filter alone, like a Fluval 405 or equivilant, do it? The tank does have 50 tetras/rasboras and a few assorted ancistrus in it, but water quality seems good.

Thanks for the help,

-Russ

Hi Tom and Russ.

Well my english is no good ok ;-)

I'm from Brazil and I have a Tank whit Discus and plants:

- HC ( Hemianthus Calitri);
- Glossostigma;
- Ludwigia Pantanal;
-Higrophila Balsamica;
- TOnina .sp Belem;
- Tonina Fluvitans;
- Limpholia sp Mini;
- Amania Bonsai;
- Amania Senegalense;
- Christmans Moss;
- Cladophora;

And I used a lot CO2 because I need to my plants, I used just at day.

Once in my tank my discus are dark and respiration was a lot higher too, in my case was caused by Amonia. And after readding the book "Discus The Naked Truth" by Andrew Soh I see that's correct about Amonia.

Well Discus need and like a lot of change water!! Maybe you can do this more times!!!

[]s

Alexandre (Ramsés II)

My actual tank ---- 250 l ( 100cm x 50cm x 50cm)






Discus:

2 - Cobalt Blue Solid
2 - Red Malboro
1- White Diammond
1- Red White

NH4 is certainly a possible factor.
I do suggest large water changes as a matter of routine as it is.
Good plant growth should negate any NH4.
Plants actively remove it.

Some good rippling and more CO2 addition will help.

You loose some CO2 with more movement, but the trade off is worth it.
Then you can have good stable higher O2 and good stable higher CO2.

What you do not want is variation with O2/CO2 ratios.

Regards,
Tom Barr

I don't know what the rest of you find, but IME any new fish added to a planted tank with CO2 tends to gasp until it acclimatises.

I've been stocking my newly set up tank slowly and every time, the newly added fishes head to the surface. It's not usually until the next day that they recover. Most LFSs seem to keep them in tanks with with little greenery and airstones running. I now try to add them late at night with the CO2 and lights off. By morning they're fine.

B,

I think that's true. With the discus, I stopped the CO2 for a day, when I saw their initial reaction. However, the surface movement seemed to remedy it. Also, I think most of us use canister filters and it has been my experience, even before I was using CO2, that they lower O2.

-Russ

any filter system will use some O2 as thats how the nitrifying bacteria metabolise. Canister filters, unlike a sump arrangement, will not replace any lost O2 with water exposure to the air, obviously. surface movement is really the most important thing, it doesnt have to be much either to make a massive difference.

I'm rather fond of surface skimmers, and the Eheim surface extractors. The latter is quite capable of keeping up with the average trickle filter for dissolved oxygen but you do have to increase the flow rate a bit.

Personally I feel as long as the current doesn't uproot plants or blow the fish out of the tank "Have at it " ! You develope a knack displacing volume discreetly.

It is really quite amazing just how well brisk surface movement increases the O2 level as well as any trickle filter. My pet peeve W/ trickle filters is that the gravity drain of the overflow tends to impede my prefered flow rates. I can easily push 700gph. through a 65 gal. given half a chance ! Grtz, Prof M