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[APD] Re: More fish die off

Cardinals tetra can be very hardy fish and live up to 3-4 yrs (10 years from one report) in tanks that take into account their needs. What works best for full tilt plant growth doesn't work for cardinals, especially newly bought ones.

I lost two schools of Cardinals back to back with water changes. I have a heavily planted tank, 3 wpg, pressurized CO2, usually 4-5 kH and 7-9 gH, temp 82 for discus and loaches. I follow many recommendations here and do 50% water changes every 5 days. The plants grow fast and pretty well. Our city tap water is moderately soft in winter but very soft (in spring/ summer) lately around 1 kH and under 1 gH. It does contain choramines. So when I water change I use a python to temperature match and I add usually 1 tsp baking soda (in winter) to the incoming 30 gallons or so of tap water. I also add 1 tbs of Amquel (old formula) for the Cl+ choramines. So really nothing should fluctuate as I do the water change. Then at the start of summer as the snow melt started and EBMUD (water co) mixed in well water the water hardness halved. Since I was still doing 1 tsp baking soda , I was having kH drops of 2 degrees, with no change in temps or pH (it's is on a SMS 122 controller at 6.8)

Just this change in hardness was enough to kill the cardinals I think. I lost half the school of 30 after 1st water change and the remainder after the second. Bought replacements and repeated same mistake with another 20. I didn't notice how much the tap water had softened and was buying cardinals just as EBMUD changed to the summer mix. I am currently adding 2 tsp baking soda and 1/8 tsp epsom salt (twice what I needed just 3 months ago.)

I have since got 20 new cardinals and setup in their own tank which is low light, no CO2, 82 F . They get only 25% water changes biweekly (6 gal:25 gal) but I do not do any hardness adjustments. I just left the tap water soft (0.9 kH and about 1-2 gH) as is. I do test before and after. All I do to that tank is use Seachem acid buffer to drop pH to 6.4 and I add a few grains to a 3 gal bucket to drop incoming water pH from 7.8-8.2 to around low 6's. The 2 year old huge Java fern (regular variety) in the tank isn't doing very well after 6 weeks of this it was grown in in another tank (76 F under 1 wpg with 2 15W 5500k normal florescent tubes, low pH, but harder water ) , but the crypts, najas, and hornwort are growing ok.

I think I am burning the java fern since I put in a Smartlite retrofit kit in the Eclispe 2 hood to add a reflector and switch to compact florescent bulbs. It came with a 10,000K and blue actinic dual 32W bulb. I planned on replacing it with a 6700K but I really like how it brings out the cardinal's colors. That maybe isn't going to work much longer.

So take home message, be cautious when making water changes with Cardinals and match the before and after closely.

As I pointed out to Tom Barr a few weeks ago "FAILURE: Maybe your (my) only purpose in life is to serve as a warning to others"
Michael O. Skidmore
Alameda CA
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