Differing Water Parameters

[hedylogus]

I have 2 tanks: a 20 long and a 30 gallon. Both are exactly the same except on 2 accounts. 1) the 30 has a piece of driftwood that the 20L does not; and 2) the 30 is filtered by a TetraTec PF, while the 20L has a Whisper PF.

The water parameters are as such:

TAP: pH 7.0, 2KH, 8GH
30g: ph 7.0, 2KH, 10GH
20L: pH 7.3, 4KH, 10GH

I can buy that the driftwood might cause the differences between the two tanks, but why the differences from tap?

-Matt

[tjudy]

:)
Do both tanks have the same gravel or other decorations? Do both have the same types and numbers of fish? Are you water changing with straight tap, or RO and tap?

GH is a measure of total dissolved solids. The driftwood will likely affect that, but the effect should diminish over time. The KH is a measure of carbonate hardness, or buffering capacity. The tank that is 7.3 pH and 4 KH makes sense, because the increased KH is keeping the pH up. How the KH is increasing I do not know.

Do you get a lot of evaporation? If you do, and you do not top off with RO before you water change with tap, you could be accumulating KH.

[aspen]

is the first measurement tapwater that has been aged? if not the kh and the ph will be lower, than after aeration, hence the higher measures in the 'resting ph' of the 20 litre than the tap sample. the driftwood will add tannins, hence the lower kh and ph of the 30 gal. is the water in the 30 browner than the little tank? that stuff is good for apistos, and other soft water fish. i use peat, but driftwood will do a similar thing.

rick

[hedylogus]

Ted,

Both tanks are bare bottom with the same decorations (PVC, terra cotta pots/saucers, and acrylic yarn "mops") except for the driftwood. The 20L has a trio of Cacatuoides. The 30g has 6 small tetras, 3 Curviceps, 2 Kribs, and a cory. I would have thought the higher load of the 30g would raise the parameters due to the increased waste load--apparently not. Water changes in the 30g are done with straight tap, but I add 2 gallons of distilled water with every water change for the 20L (which I thought would help lower my parameters). I change roughly 1/4 of the water in both tank weekly. As far as evaporation is concerned, both tanks are relatively the same (due many to surface agitation from the power filters).

Rick,

No, the tapwater wasn't aged, but I live in the middle of a big city and I'm supplied via the city's public water system. I was under the impression that aging was a concern for well water users only. I'll have to experiment. As for the driftwood, no visible tannins.....anymore. My slighly brownish tint disappeared roughly 2 months ago.

Any thoughts???

[aspen]

i live in toronto, and my water is 7.2- 7.4 straight from the tap, and 7.8 - 8.0 after aging. the dissolved gasses, like f/i co2 are to blame.

i assume 20L means 20 gallon long? 3 cacatoides would be pretty cramped in a 20 litre. (5 gal)

have you checked nitrates? high nitrates will lower ph. (nitric acid.)

rick