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Re: long term subtrate experience

     << Date: Fri, 11 Apr 1997 10:56:55 -0400 From: Michael Eckardt 
     <mike at odg_com> Subject: long term subtrate experience
     I have been wondering how long the substrate of a planted tank is 
     So the questions are:
     What are your long term (i.e. > 2 years) experiences with your 
     substrate? Should the Dupla style of substrate be recommended for 
     anticipated long-term setups? Are the "rich" substrates more 
     appropriate for shorter term setups, experimental tanks, or plant 
     propagation tanks? >>
     I think the whole point of the Dupla system is to provide constant 
     conditions as much as possible and this is one of the big advantages. 
     With the "richer" substrates, you will always notice changing 
     conditions related to nutrient levels and long effects which are 
     difficult to measure or identify; I'm talking about organic substrates 
     here. If you were using chemical fertilizers in sand/clay/(?) you 
     might be able to maintain more consistent levels by periodically 
     adding clay enriched balls or sticks or some such thing. Still, you've 
     got to wonder what happens to the sulfates in those chemicals. I 
     suppose that a lot of the sulphate will be either consumed by the 
     plants or removed with water changes as a dissolved salt.
     When we talk about "rich" substrates, I think a lot of people have a 
     misconception about what this means. By terrestrial standards, this is 
     not a rich soil at all. Undecomposed manure, organic material etc has 
     the potential for creating some REALLY bad conditions. Probably what 
     you want is organic material which has gone all the way to becoming 
     humus and is really not that rich. That will give you a high CEC and a 
     low fertility which will not change a lot with time. You won't have 
     the high levels of nutrients that you have to be concerned about with 
     most of the organic materials which you are forced to choose from. 
     From this perspective, perhaps the best choice would be natural soil; 
     soil which has sat for many years in an undisturbed condition. No 
     manure; no compost. But that may not be easy to find especially when 
     you live in a city and you're stuck in the mountains with a lot of 
     glacial till for local soil. The second best choice might be earthworm 
     castings (EWC) or peat. It turns out that neither of these is very 
     completely composted (but much better than manures) and so you're 
     still going to have a LOT of biological activity happening for about a 
     year. Then it would probably settle down and become a "low" fertility 
     substrate that is pretty stable. Of course, you can still add 
     fertilizer to the substrate by other means and you still have fish 
     poop and detritus. 
     The thing about a fertile organic substrate is that it has a lot of 
     nutrients especially nitrogen that can really give your plants a kick. 
     The problem is that there is a much larger potential for things to go 
     wrong. Really wrong.
     Let me describe some scenarios I've experienced with small tanks. I 
     set these 2 gallon tanks up as quarantine tanks for plants after 
     bleaching so I could observe the plants to be sure that all the algae 
     was gone. Sounds like a great idea in theory but in practice both have 
     turned out to be disasters. Don't feel too bad; what's bad for me has 
     turned out to be good object lessons for y'all.
     The first tank had several Crypts after a short bleach treatment in an 
     early experimental clay/EWC/sand substrate with clay fertilizer balls. 
     The big problem was there was way too much fertilizer in there and it 
     turned into a mush of BG algae. Also I couldn't fertilize with CO2 and 
     so I tried using an airstone to circulate the water. Everything turned 
     to mush but the Crypts being adapted to such horrible environments 
     took it in stride, melted all their leaves but the thick roots 
     remained alive. After a lot of washing, I transfered the remnants to a 
     large tank and they did recover quite nicely. This would not have 
     worked with any other plant I suspect.
     The second tank was another experimental clay/EWC/sand substrate with 
     only 6 granules of fertilizer. This time I rigged up an inverted jar 
     in the corner using a coat hanger and bubbled yeast CO2 in. I also had 
     daphnia and lots of snails to eat the algae. I added 4 lightly (60 
     sec) bleached baby Echinodorus osirus specimens and all went fine for 
     a few weeks. The plants showed moderate growth with new leaves. The 
     CO2 acidified the water and the daphnia all died. Ok, no big deal. The 
     water wasn't green anyhow. Heavy growth of algae on the sides since 
     this tank was on a shelf close to the big MH light and getting plenty 
     of light. (not a good idea) This made the snail get very big and fat 
     and they laid LOTS of eggs all over the leaves of the plants. Oh-oh. I 
     took two of them out since there appeared to be no sign of the 
     original algae and the plants looked like they had established some 
     roots. I washed the snail spawn off as good as possible and planted 
     them. I notice that the old leaves seem to have suffered some melting 
     or damage perhaps from the snail spawn or my treatment of the plants 
     with rubbing and cleaning. Both are alive although touch and go.
     Not so good for the other two. After the disturbance in the tank, the 
     water was VERY cloudy from the clay. I didn't panic; figured it would 
     settle in a day or two and added more daphnia and small amount of 
     organic water to help the clay to settle. After about a week, the clay 
     still has not settled and deprived of light, the plantlets could no 
     longer produce oxygen and I reckon their roots succumbed to toxic 
     stuff produced in this "rich" substrate. When I pulled them last night 
     there wasn't much left. There were these brown things that once might 
     have been plants but were now mostly mush.
     Now and experiment that worked. A small margarine container was filled 
     with a mixture of local clay, sand and the washings from the EWC soil 
     as per Paul Krombholz's method for preparing soil. This method removes 
     almost all of the organic material from the EWC soil since it's still 
     fibrous and too large to pass through a screen. It was a laborious 
     process. I think I enriched it a little with some EWC or fertilizer; 
     can't remember. Put in a layer of white silica sand and a small Crypt 
     and kept adding water carefully and its been sitting to one side under 
     the strong MH light. It's not huge but its healthy and the leaves 
     alternate between being submerged and emerged. I might repot this into 
     a regular flower pot and try growing it as a terrestrial plant for a 
     while just to see if it will live and maybe flower.
     A) be careful with clay; get a cloud of it and you can kill off your 
     plants and fish if you have a transitional organic tank. (one that is 
     still in the process of heavy decomposition) Prevent light from 
     getting to the leaves and they stop photosynthesizing and have no 
     protection via oxygen in their roots. In a quarantine tank, maybe 
     don't even bother with clay at all.
     B) a rich transitional tank is no place for a few small plant cuttings 
     that are possibly recovering from bleach. Far better to have a small, 
     established natural soil, or fine gravel tank with CO2 and low 
     nutrients for a plant quarantine. Probably the best way to do that is 
     with a tank full of H poly to keep the soil sweet or to condition 
     C) less is better; less clay, less labile organic material, less 
     nutrients, less CO2, less light. A 20 watt compact FL probably has all 
     the light you need.
     C) a small tank is no place to be fooling around with an unstable 
     system. A fine gravel tank filled with water from your main tank 
     probably has all the nutrients you could need. 
     I wish we had a better way to deal with removing organic material from 
     soils than the laborious method of trying to force it through a 
     screen. Maybe my EWC just has too much fibrous material in it and I 
     should use regular dirt. I think that's also why Paul doesn't see the 
     high nitrogen levels from his soils that I do. He uses liquid nutrient 
     extractions made from soil and compost that are very powerful and 
     added in small doses.
     Steve Pushak   in Vancouver  where spring is temporarily on hold