In article , "SteveG" wrote:
The substrate in my 29 gallon tank (30"L x 12"W x 18"H) is 1.5"
sand/laterite mix and 1.5" sand. The brand is Tahitian Moon Sand by
Carib-sea. The tank has been setup for 3 months now. CO2 injected
(presurized tank w/ Nutrafin bubble counter/diffusor.) Lighted by 2-24" 17w
T-8 flourescent bulbs (Zoomed brand Flora-sun and Ultra-sun) which are
powered by a Hagen brand electronic ballast. PH around 6.5. Soft-medium
water.

I have read that sand substrate compacts over time and causing anaerobic
areas in the substrate. As a result, toxic gas bubbles (H2S) are created.
And was also told to poke the substrate in different areas to release these
bubbles. I do see bubbles coming out near the base of the plants but I'm
not sure if these are the toxic bubbles or just oxygen bubbles that has been
accumulated. I see my sword plants give off bubbles from time to time.

If its H2S, you will know it. Even a small bubble of H2S you will be able to
smell (rotten eggs).

My questions a
a.) What effect do the anaerobic areas have on the roots of plants or on the
whole plant? (I have Echinodorus quadricostatus ''magdalenensis'',
Cryptocoryne beckettii, Echinodorus 'Rubin', Echinodorus osiris, and an
assortment of stem plants.)

If everything is growing, then the setup is probably working for you and I
would be inclined to leave as is.

b.) Putting Malaysian trumpet snails will help me with the task of keeping
the substrate aerobic, but I would prefer to put fish instead. I have 3
Corydoras aeneus that sifts through the top layer, about .5" inch deep
(they're only 1.5" long as of the moment). Any other suggestions?
(Their other companions would be an otto, 2 SAEs, 6 diamond tetras, 3 cherry
barbs, and a pretty happy and bossy discus)

Assuming that your tank can handle more fish, add both. For practical
purposes, MT snails will not have an impact on the amount of fish you can
keep. They will also for the most part stay on the bottom, and don't clutter
the glass like other snails do (you won't know they are there unless you look
for them).

Thank you for taking the time to read the whole message, and any help is
greatly appreciated.

SteveG



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-John