Hi all,

I hope someone can help or advise. I've a 90L tank (don't know what it is in any type of gallon), 3 fishes in it - 1 bristlenose (about 2 inches), 1 large fantail (about 2 1/2 inches to base of tail) and a little fantail (barely an inch with the tail).

The tank is fairly new, about 8 weeks old, cycled with cycling aid within 3 weeks (!), its been sitting at Ph 7.4- 7.5, Ammonia 0, NitrIte 0 and NitrAte 5 for the last month. The filter is Eheim 2213 (440 L/hr, it's an overkill but I figured it's better than having to buy another one in the future when I upgrade again ). On recomendations of the aquarium shop staff I ditched the carbon out of it, however was told to add this purifying thing 2 weeks ago ( "Purigen 165"), apparently some kind of synthetic purifier, I had a problem with yellow colour leeching out of driftwood, it certainly took care of that!

The fish were very happy, eating like pigs, the plants growing like mad. However, something has happened in the last 2 days and I am not sure exactly what... was very busy at work, didn't have any energy at night to even notice. My filter output usually sits just above water level, pushing lots of air bubbles under the water, airating the tank - but it's been a little too full over the last week and there weren't any air bubbles coming in.

Anyway, did a 25% change tonight, and noticed that afterwards the Ph was 6.8. Ow. The large goldie was swimming frantically and then sitting under a plant and gulping. I put in some stress coat to soothe him, and he was eating fine too - but then went back to his corner to gulp. Also, his fins got frayed a couple of day ago very suddenly and quite badly.

So, I am wondering... is this because of lack of oxygen? Or this Purigen thing? Or Ph? And if its a Ph crash, what do I do to fix it? Someone mentioned bicarb soda - how much do I need to put in to fix this? I don't have time to go to the aquarium shop for another week (it's too far), is there something I can do to fix this now? The fishie has survived Ph crash before, but I would rather he wasn't do upset...

Thank you!

Was there a change in the tap water pH?

I know that when you re-charge your purigen with bleach, after you rinse and soak in Prime, you also have to soak it in a pH adjuster. Although, my impression was that the recharged Purigen tends to boost the pH up - not down? Is your purigen all dirty brown and in need or re-charging? Perhaps this has some effect on pH?

Have you added any salt to the tank? (although I don't think that effects purigen)

Ok, you have a 50 gallon tank. Add 1 teaspon of bi-carb per 10 gallons (5 teaspoons), wait an hour and test your pH. Repreat until you reach your desired pH level.

Woooo Anette he has a 90litre tank (20USgals) not a 50gal tank adding that much bi-carb would be over kill.
You will only need 2 level teaspoons of Bi-carb and then as Fishmerised has said test ph until a desired level is reached. Bi-Carb is only a temporary fix if you wish to make it permanent i would purchase some crushed coral from your local pet store or lfs.

Ooh sorry!!! It's my head cold, please excuse me. Even after reading dan's post i had to think r-e-a-l-l-y hard to understand. Time to go to bed. Nighty nite!

That is okay we all make mistakes. My Asthma has flared up after all the back burning in Sydney this past week i guess that is only reason i am up as i can not sleep which would be the only reason i noticed that tincey mistake.

Oh cool, thank you for that! So it's 2 level teaspoons (in total), wait for an hour, test Ph, repeat until it's 7ish. Right. I think I can remember that

Don't know what the tap pH levels were, sorry... have been very slack, haven't measured it for a long while. Don't know about the Purigen thing, the fish shop people said to recharge it every 2 months and it's only been in the filter for 2 weeks. Besides, it's a pain to pull it out, I will have to unplug everything and pull out and open up the canister.

Dan, I know how you feel re: lung dramas. I am in Brisbane, and with the season changing, I am getting all the joys of hay fever and occasional asthma flares too. It sucks, I hate that "tight lungs" feeling...

Ok, now will go and dose the fishies.

P.S. Ok, have dosed the fishies, now will wait and see. I will keep an eye on this ph thing too, to make sure it's steady from now on. I wonder what caused it. The big fishie is doing fine, he tried to munch on the test tube when I went to get the water and then got interested in bicarb. Typical golfish, what can I say, trying to eat everything.

Also... I get kind of worried about putting stuff like bicarb soda into the tank. I know it's just chemicals, but still. It's not like I am baking a cake, right?

Thanks again for the help, you are awesome!

Another place to put the purigen where you can keep an eye on it is to hang it right beside the filter water return. That way it still gets all the water flowing over/through it and you don't have the hassle.

Purigen is great to clean up a dirty tank, it's quite possible that yours does need recharging already if it has soaked up all the tanin from the driftwood. Driftwood lowers pH, so that could be your problem.

I say, check the purigen, it's easy to see by the colour if it's dirty. You might want to get a smaller piece of driftwood too and add some crushed shell/coral to your tank to help buffer the pH and keep it stable.