Finally got my api master test kit... results... need help

Ok so i am sooo glad i finally got my master test kit... but im not really that happy with my results.... so here we go, im gunna post my results for all 4 of my tanks.... any suggestions welcome.

30g Community tank
pH-6.4 ---- i know it should be at 7, just did a water change 4 days ago 2
Amm- 0
N2-0
N3-40 -----what to do about this??

100g South American Cichlid tank
pH- 7.4-7.6
Amm-0
N2-0
N3-20

125g Semi-Aggressive Planted tank (just set up 2-3 weeks ago)
pH-7.2
Amm- 0
N2- 0.25 -----help?
N3-10 -----??

48g Goldfish tank
pH 7.4-7.6
Ammonia 0
Nitrite 0
Nitrate 10




My biggest question is with the 30g. we just checked it with our regular API pH test kit yesterday and it read 7. Now the new test kit is saying 6.4?? and Nitrates are at 40??! My boyfriend doesn't understand why its so messed up cause he did a water change 4 days ago. I tried to say we need to do one again, and he doesn't believe me. What do you guys think?

Hooked Newbie said:

baseline your tap pH by letting a cup of it sit out overnight and then testing.

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good idea... thanks for the advice!!

DrVader said:

do you happen to have a Carbonate/General Hardness measurement kit? Low carbonate hardness can contribute to pH instability.

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No, i actually have idea what your talking about?

jm1212 said:

they mean KH and GH (may not be any more helpful...)

basicly, both aspects are measured together in the for of pH. testing GH and KH will tell you how well your water can buffer to a certain pH.

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ummm ok i kinda get it? Is it a completely different test i can get at a lfs? and is important??

DAVIDFBT said:

This: GH/KH Test kit. Basically, for people with demanding fish (Discus and African Cichlids mostly) and who are running CO2 with their tanks.

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Hmmmm we are about to set up the co2 in the 125 planted... so maybe i should get it.. THANKS!!