Re: PMDD's and nitrate
To: Aquatic-Plants at actwin_com
Subject: Re: PMDD's and nitrate
From: psears at NRCan_gc.ca (Paul Sears)
Date: Thu, 24 Oct 1996 08:40:40 -0400 (EDT)
In-Reply-To: <199610230739.DAA10317 at looney_actwin.com> from "Aquatic-Plants-Owner at ActWin_com" at Oct 23, 96 03:39:07 am
> From: Stephen.Pushak at saudan_HAC.COM
> Subject: PMDD & Nitrate concentrations
> I have a week old _experimental_ soil substrate which I have recently
> set up. I have used PMDD at a reduced dosage (but not reduced
> enough) for the last week. Recently I've been measuring various
> parameters and find that I have approximately 100ppm nitrate in
> this tank.
How long has this tank been going? The implication of what is
written above seems to be that it has only been set up for a week.
If so, the contribution of the PMDD's to the nitrate there now is no
more than a few ppm.
> o monitoring NO3 regularly is critical for proper use of PMDD!!
I think we pointed this out in the original posting on the
subject. Monitoring nitrate concentrations isn't a bad idea in _any_
tank, and will be more important still in a planted tank, where
nitrogen _must_ be available for the plants, yet accumulation is
to be avoided.
> Suspend the
> addition of nitrate and probably all nutrients and micronutrients
> in a soil based substrate until it becomes clear that the
> plants are becoming nitrogen limited.
I'm not wildly enthusiastic about the "mixed" approaches to
plant growing. If you have a fertile substrate, then why add things
to the water column? I use the water column approach mainly because it
is very easy to adjust, and I don't have to tear the tank down when
the substrate wears out.
> o in closed systems where water changes are minimal, we need to
> be cautious about nutrient additions. These can probably be
> accomplished (with possible exception of Ca) by regular feedings
> of a balanced fish food diet (or other organic materials in
> fishless tanks)
"Balanced" for the fish may well not be "balanced" for the
plants. Do water changes, throw out plant material as it grows; the
faster the turnover of water and plants through the tank, the less likely
is the buildup of anything.
> My advise is stick to a single method unless you know what
> you're doing or like experimenting.
> If you use small containers
> for your Crypts or other plants, you can experiment with
> much more freedom and I would encourage people to use this
> approach and share their results (good and bad).
Is that what you were doing in the tank mentioned at the beginning?
Paul Sears Ottawa, Canada
Finger ap626 at freenet_carleton.ca for PGP public key.