water readings with 2 questions

[huxta]

75 gal
ph 6.8
amon & nitrite non-detectable
nitrate 40

30 gal
ph 7.2
amon & nitrite non-detectable
nitrate 20

Why would ph levels be so different. I guess I don't know what causes levels to fluxuate.

I have lost two fish in my 75 gal in the last 2 days and another 2 fish a month ago. The water seems fine with the exception of nitrates being high but within the toxic limits.

 

[Cheese Specialist]

I have different levels in all y tanks! 7 in the biggest, 7.3 in the c/w and 7.5 in the small tropical!!

I think the low one is due to bogwood but I dunno about the rest.

You shouldn't worry as long as it's acceptable levels and your are I think.

 

[cation]

Too much decaying organic material can cause a lowering of pH as well. The only reason I mention this is that the pH is lower in the tank with the higher nitrate level. You may want to try increasing your water changes/gravel cleanings. ( just in the tank w/ the higher nitrate.)

 

[Changes-In-Latitude]

Metabolic products, fish food, plants/wood/etc decaying can all eventually wear down a waters buffering capacity. The nitrates are a little on the high side which correlates with the lower pH. Under 25 ppm is a much more ideal range.