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Re: Nutrients in Substrate or Water?

A M Moore asks...
>What is the general feeling of the group regarding nutrients in a fully 
>planted aquarium - PMDD to be added to the water daily, rich substrate only 
>OR both ??

If you are interested in growing Cryptocorynes especially the less common 
ones, you would probably benefit using a peat and soil style substrate. Most 
plants grow faster with substrate nutrients but it is not always what you 
want since you still may have to trim all those water weeds perhaps on a 
weekly basis. Using soils etc. is not for novices I think we all agree. Also 
there are situations where you just have to make do with the materials at 
hand and higher cost technologies are just not viable. Another reason might 
be you want a low tech tank without CO2 injection and maybe without fish or 
with fish which tolerate low oxygen conditions.

Suppose you want an all around tank with lot of kinds of plants and you've 
decided that you like the idea of using soil. Ok, go ahead and use it but 
don't go overboard. Too rich a substrate can cause you lots of problems. Clay 
and other materials can turn your water into brown soup if you get it stirred 
up so you've got to use common sense.

If you want the safest, guaranteed approach and you have a reasonable budget 
to work with, you should pick up The Optimum Aquarium Book. They use laterite 
and only the organic materials from the fish in that substrate. I think there 
are also starter tablets for the substrate too so even this method enriches 
the substrate. A common theme to notice is the use of iron oxides (laterite) 
in the substrate! The whole objective of that methodology is to have a safe, 
repeatable, reliable system that aquarists anywhere can use regardless of 
their location, water conditions etc.

I think also the term "rich substrate" is really misleading. I don't think 
anybody really wants a truly rich substrate. This is a sure fired recipe for 
a nitrate concentration of 100 - 200 ppm and blue green algae or worse. It 
can be managed but if you get an infestation of filamentous algae, you've got 
serious problems if your Fe concentration in the water gets too high. I don't 
recommend it. It's not necessary. I've experimented with rich substrates 
because I wanted to learn about the factors that go wrong, not because I 
think they are the best ways to go. I hope you weren't referring to me when 
you mentioned an APDer who said it was the only way to go. I think a lot of 
people read things here and get the wrong idea because they haven't spent the 
time to read enough of the articles to get a full picture.

I'd also like to point out that you can have safe and successful low, and 
medium fertility substrates using soil. Peat is an interesting additive to 
try because it does not release large amounts of nutrients. A peat/soil 
substrate I recently set up on the weekend shows no measurable nitrates after 
three days of submergence. The peat I used was ordinary sphagnum peat moss.

Yet another way to go is to add small pieces of Job's fertilizer sticks or 
clay balls with slow release fertilizer inside them to increase the fertility 
of a substrate for selective high feeder plants like sword plants or Crypts. 
It really makes them take off.

Yet, yet another way to go is to use soil, peat etc in pots like Karen does. 
This is a really good way to go because you can mix and match to suit the 
needs of your plants.

BTW, I use a modified PMDD technique. I changed the dosing method; I do it 
with water changes now and I don't add nitrates. I only add chelated Fe if 
I figure it's necessary. I try to minimize Fe in solution as an algae 
prevention strategy. As I go along, I modify things. If I figure a 
particular plant needs more nutrients for it's roots, I can spot feed it. I 
just love to tinker but I don't reckon that's for everyone. Most of the 
time things work well and I've only had one small disaster where I lost a 
small tank of E osirus when I stirred up the clay and everything turned to 
mush on me.

Steve in Vancouver