High gh/tannins/dying fish

[HollyH]

Hi everyone! Ive had tanks for several years now but this is an issue I haven't run into before so hopefully some of you have.

I used my canister filter and decorations from my 40g to seed my new 75g. All was well for a few weeks. I bought 3 pieces of Mopani Wood to decorate. A day later my water was yellow. OK, new wood is going to leach tannins. I changed my carbon to clean it up and did a water change. I left the wood in since it wasn't effecting my ph, just the look of the tank. Then I started losing fish.

After several fish I pulled the new wood and decorations from the tank to get control of what was going on and did a 50% water change. The wood has been out of the tank for almost a week, I added an immersable filter with carbon only in it and the water is still yellow. The only wood left in the tank is a piece of wood I've used in my tanks for years without issue. After the water change i lost almost everyone in the tank within days (osmossis maybe?). All of my levels are as follows:
Nitrates 20
Nitrites 0
Ph 7.0 and stable
Kh 80
Gh 180

-Now that the new wood is out of the tank and I added more carbon, the water should have cleared up but it hasn't. Could my drift that I've used for years be breaking down after years causing the color? I had no tannins in my 40g, why all the sudden would this piece of drift breakdown so fast?
-why wouldn't new carbon pull the color out at all?
-I want to do a water change, 25% maybe, but haven't lost a fish in 24 hours so I also don't want to touch it. If I lost the fish from osmossis, a water change is only going to cause a quick shift in gh and I'll lose fish again.
-Should I try to bring down the gh before any other water change?
-Im boiling the tannins out of the new wood now, I'm giving it a 6 hour boil. If the tannins are no longer leaching, my gh should stabalize correct?
-Why would my gh jump so high but my kh and ph remain stable?

What am I missing?!?! I can't get it under control.

 

[ScotJudd]

Hi.
Gh of 180 (approx 10 deg) is not that high. What fish did you lose? Most tropicals, apart from specialist fish will tolerate that Gh. Did you have a sudden increase in Gh that shocked the fish? Have you checked the Gh of your source water, probably tap water? You must have added quite a lot compared to a standard water change when you up-sized. Insulting question, but did you dechlorinated the new tank water, a possible error when setting up the new tank.
As for tannins, I would recommend Seachem Purigen to remove tannins. It's not as cheap as carbon but extremely effective. I use it myself and was pleasantly shocked at the difference in just 24 hours.



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[HollyH]

Yes, I declorinated the water for the new tank. I thought about it and realized how easy it would be to miss that step and defeay the whole purpose of seeding the new tank. Good call.

I lost my dwarf rainbows, hillstream loaches and all my neons. My Matagascar rainbows are happy as can be in the tank right now as is the rainbow shark and cories.

I have some purgin that just needs to be cleaned to be used again. How much would you use to clean up the tank? I have 2 fresh bags in my canister and a carbon pad in the internal filter.

The tap levels are in line except the gh which is 60. My only other thought of what's increasing the gh is I threw a handful of pebble stones in the sand, maybe one of the stones was limestone stone that got mixed in somehow? Would the gh difference between the tap and tank be enough to cause osmosis on a large water change do you think?

 

[ScotJudd]

Hi again,
I have one bag of Purigen in each canister and change it when very dark brown. I refill the bags from a larger jar of Purigen and reseal the ends with a large food bag clip. That's worked for me and the bags themselves last well over a year. I don't recharge Purigen myself, too much of a phaf and I don't like bleach anywhere near my tank or equipment. Many others will disagree with that but you have to go with what you're happy with.
You could be right about a stone increasing Gh but I would have thought it would be a gradual process and not a quick change which could shock the fish. Without knowing the Gh in the old tank and then in the new tank it's hard to comment on osmotic shock being the reason for the fish loss.
Before I move fish from my QT, they stay in there for 6-8 weeks as I like watching them, I check all parameters in both the QT and the main tank. If there are any noticeable differences I replace one bucket of QT water with one bucket of main tank water every day until they are equal. Then they can just be netted and swapped over. The acclimatisation period could be 3 days or more, but is done in the QT itself.
I don't know if any of that helps. Hopefully.


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