Water Problems

[slurik]

Hello,

I have been trying to get back into fish keeping this year as a hobby. I decided to go with a 40 gallon bowfront, kit aquarium with a penguin biofilter, and heater.  I wanted something simple, and perhaps raise some large fish and move to a much larger tank in the future once they grew up a bit.

I setup the tank in mid-May, and did the appropriate cycle time before I started adding fish. When it was time to add fish, I decided to get a half of a dozen zebra danios, a good hardy fish but inexpensive if there were any issues. They seemed to do fine, so I added some gouramis and a severum.

Within 5 days the fish began to look quite lethargic, but did not have any signs of new tank syndrome. There seemed to have been no ectoparasites at all. The fish did not seem to demonstrate any real distress, like flashing rocks and substrate. One by one they just got very lazy, they hid, then died. Their colour did not seem to really depreciate and they looked alright... but day by day another one bit the dust.

I broke my damn heart watching the cichlid die.

There is no ammonia in the tank, and there is only a small sign of nitrate, with no nitrite.

I have been depending on PetSmart for free water tests. I have a pH test meter which reads my tap water as 7.1 and my tank as 6.5. this sensor was calibrated recently.

I top up the tank as it evaporates, and perform a 25% odd percent water change every 2 weeks or so. I am under suspicion that there would be an issue with my rocks. I was very careful when adding them that they were boiled and baked to destroy anything alive on it. However I have chosen rocks that I have collected locally on geology work, and suspect that the odd mixture might cause some problems.

I have added about 10 pounds of pure marble. I have initially concerned myself with CaCO3 being able to buffer the pH, but after research it seemed to be negligible and I have not been reading any jump in pH.

I have added 25 pounds of Perthite. This mineral is an intermediate Feldspar, which contains KAlSi3O8, NaAlSi3O8, CaAl2Si2O8. Orthoclase, Albite and Anorthite respectfully. This then caused me to be worried about Al issues, but Al turns out to be incredibly insoluble at any reasonable temperature and has only been demonstrated to have much mentionable saturation point below 400 Deg. C.

I bought a hunk of wood off of Amazon too. I boiled and baked this, though it floated at first, it has sank after a few weeks of exposure to the water.

I have 40 pounds of black Carib Sea Super Naturals sand. It is stated to be safe in salt and fresh water. It is notably magnetic, and will readily stick to my NimbleNano if I'm not careful cleaning the glass.

Please help me with any ideas that you have.

[Jody]

Hi Slurik,

   Sorry to hear about the issues you are having.
I am certainly no stone expert so hard to say what issues they might cause. I seem to remember someone in the past mentioning that marble isn't great, because it often contains other minerals that can leach in the water, but that was a long ago conversation which may be jumbled in my memory..lol

If pH, ammonia, nitrites and nitrates are all reading fine, then clearly it is something that we are not testing for. Assuming that the tests were done correctly of course. You mention that you cycled the tank for an appropriate time before adding fish. Cycled as in let the tank run, or cycled as in added something to create ammonia to build a bacteria colony to help break down your fish waste? 
  6 zebra danios in a 40 gallon would create very little waste, so even as canaries in the coal mine it would be likely they didn't produce enough waste to cause an issue. When the gourami and severum were added, depending on size, they may have increased the bioload by a huge amount.

I guess the easiest way is to remove the rock work and the wood, and start from there. Some good quality carbon or absorbing resin may help remove toxins in the water, and a Poly-Bio Marine filter pad could do the same, and may in fact give you an idea what the toxin is (these are available at Big Al's and online).
http://www.poly-bio-marine.com/faq.htm

The sand is pretty neutral and should not be causing any issues. I use it in many of my tanks, and it works well.
What kind of wood did you purchase? Was it previously used in an aquarium? Treated in anyway?

Sorry, lots of questions, but sometimes it is the simplest question that solves the problem.

Thanks
Jody

[slurik]

Hi Jody,
Thanks for your reply! The marble is in excess of 99.5% CaCO3, I have very high doubts that it would be leeching pyrites into the water body. I do also agree that often marbles would produce these problems, as pyrites and galena minerals can leech lead and sulphur into the water.

I am in the habit of feeding my new tanks as if there are animals in it for an ammonia source. I also added freshwater plants knowing fish would ruin them to have any residual bacteria transferred into my new tank. I agree that it must be something we're not testing for, so I will take your advice and remove the rocks and start from there.

The wood was purchased from Amazon.ca and was marketed as "Aquarium driftwood". It was never used before, I am unclear what exact type of wood it is but I will also remove this along with the rocks to see if conditions improve.

Thanks for your input Jody!

[bergenm]

Just a thought - the water coming out of the tap here has a pH of around 8.5, the calcium carbonate (marble) might kept your pH at this high level. Ammonia is more toxic at a higher pH, so when you added more fish to a high pH tank that wasn't fully cycled your ammonia went up and you started to lose fish.

I doubt PetSmart would run a high pH test when testing your water, so your water would test 'normal' to them.

I don't think the feldspar would cause an issue, the only problem I could see with Perthite is it comes from a road cut so it might have been exposed to contaminants.

Pulling the rocks and the wood and reintroducing slowly is a good way to go, if you are adding the marble back in you may want to run a high pH test instead of a regular pH test.