false test readings???

Question
I have a 35 gallon Amazon tank that is pretty densely stocked (about 30 fish- most very small tetras, a couple Danios and a few rosy barbs and a cory cat and one big pleco)but stable for over a year with no "mystery" fish loss. I was using quick dip test strips and my nitrites and ammonia readings were always Nil- my Nitrates were consistently on the upside tho. I read this was often because of sludge build-up in the gravel and filter ( I have a penguin 330 with 2 bio-wheels)so I cleaned out the intakes and rinsed out alot of the sludge and replaced the filter packs. At that time, I also added some Tetra Blackwater extract to the tank. I had used other Blackwater extracts before- some said on the bottle they can mess up certain Nitrate/nitrite tests- but this one failed to mention that. (Usually I tested before adding them) I tested again after my "housecleaning" and the Nitrites were at 5 ppm and rising! I totally panicked! I added Amquel+, did a 20% water change, added stress-zyme bacteria, aquarium salt- anything I could think of...the next day they were at 10 ppm!!!!I thought in rinsing the filter sludge out with tap water I had destroyed the bio filter and that all my fish were dying. More water changes, added Prime this time and bought "Cycle" and a bunch of new plants hoping these things would help. Still 10 ppm! The strange thing was- my fish were not acting stressed (aside from the fact that I had stopped feeding them and they were doing the hungry eye thing to me).My Danios even started spawning! Then I read that the test strips measure nitrogen too...so I bought a single test liquid test- with a tube- that measures JUST nitrite...and got a zero ppm result. Tried the quick dips and again got 10ppm. I began to suspect a false reading from the test strips. Should I relax and feed my fish?? Should I get ANOTHER test kit? I really love my fish- I have a 9 inch Pleco I have had for 3&1/2 years- since he was a little baby and would hate to have anything happen to the critters.....I am working on getting my Nitrates down in general ( more frequent water changes and gravel cleaning cause I know I'm over stocked. Any advice would be appreciated.

Answer
Hi Diane;

I would trust the 'liquid drops' test kit before I would the strips. Those strips are just not very reliable in my experience. Your instincts about what may have happened to your tank are right, but the strip was probably wrong. If you want to be really sure, take a sample to the fish store for them to do a test from their kits. Some stores charge a small fee, many do a test for free.

I like the dry-tab testers best for accuracy and ease of use, and then the liquid. Strips aren't even on my radar anymore. They are often more expensive per test than liquid or tablets too. "Throw 'em out" in my opinion. ;-)

At Your Service;
Chris Robbins