My Corries Got White On Its Fin Please Help?

[maisy12345]

Hi ,have had a problem with my ph going from 7.6 down to 6.6 [lost a shrimp today ] so did a 60 percent water change ,and removed bogwood from tank as thought it was the tannin causing this, re tested ph had gone to 7.6 again ,now hours later retested water ,ph gone to 6.6 again,ammonia 0, nitrite 0 nitrate 0,whats happening and what`s a matter with my cory as now noticed his back fin has got white on ,what can i put in water for it?
Just to add tank is still ina fish in cycle for three months now.
Also i`ve added a plant was i bought from a pets at home fish tank.

 

[Tokis-Phoenix]

Not totally certain on what could be causing the PH swings, but the white on the back fin is likely the start of fin rot, so treat the tank with an anti external bacterial medication. Finrot is often caused by environmental stress, in this case most likely brought on by the swings in PH (v.stressful for fish, particularly quick swings in PH).
Concerning the water quality i would advise doing smaller water changes (more in the region of 15-30% depending on ammonia or nitrite levels). Small to medium sized but regular water changes are better in cycling tanks than big but less regular water changes.

 

[maisy12345]

Thanks ,do i still do the water changes even though my ammonia and nitites and nitrates are all 0

 

[Smells a bit fishy]

Yeh, as your ph is low. Also what nitrate test are you using? API? If so thoroughly shake no.2 bottle and bang on the table for a minute, then shake the test tube for a further minute. As the nitrate test should have 3 reagents, the API test put 2 reagents in the same bottle so you need to vigourously shake it to mix the 2.

As eagle said on your other thread, that nitrates drop the ph, so the chances are you have a faulty test. If in doubt take to your LFS and get them to test the water as well.

It's very uncommon to have 0 nitrates on a cycled tank.

Hope this helps.