Re: A fertilizing mess

> From: "Eric Schoville" <ESCHOVIL at us_oracle.com>
> Subject: UGH and Soil Substrates
> the Krib says that one should never use UGH with a soil substrate. 
> Can someone please tell me why you shouldn't do this?

Soil substrates with organic material (as opposed to purely mineral
soils) are usually quite fertile. The UGH is supposed to circulate
water into and out of the substrate to draw nutrients to the roots
when they are more concentrated in the water, to draw oxygen into
the substrate and to promote bacterial activity (decay) in the
substrate. When you do this with soil, you might move nutrients
out of the substrate into the water; not what you want. Increasing
decay might be good or bad depending upon if the substrate already
was fertile with dissolved nutrients. Heating a primarily mineral
soil, low in fertility would probably be beneficial.

Also soils tend to be much finer materials than gravel
so the low pressures generated by UG heating coils won't cause
any appreciable circulation so there won't be much point from
the circulation aspect.


> From: George Booth <booth at hpmtlgb1_lvld.hp.com>
> Subject: Re: Calcium requirements in water
> If a "common target" is 71 to 107 mg/l (4-6 dGH), why is 40 mg/l a
> "safe guess"? 

I suppose that about half of the alkalinity should be Mg. Anway, it
should be more than sufficient to maintain lots of Ca for the plants
during the period between water changes and Ca additions when the
plants are using it up and it is being absorbed by organic materials.

> A "better" answer is to meet the requirements for the fish you are
> keeping.  For example, if Rainbowfish are kept in water that has low
> GH, they develop open sores and other maladies.  

Yes. In Vancouver, Seattle and in Snowy and Slippery Colorado we
have nearly rain water coming out of our taps. It's way too low
in all sorts of minerals like K, Mg and Ca. Na is also a useful
electrolyte to prevent fish diseases but we rarely add it in
plant tanks.

> 40 mg/l might be fine for plant growth but 2+ dGH is a little low for
> community tanks.  I would suggest 100 mg/l or ~5 dGH as a general
> guideline and only go lower if your fish require it. 

Many of our fish like neons, corys, otos and various algae eating
catfish come from the Amazon basin. This tends to be a low oxygen,
low alkalinity, mildly acidic environment with plenty of humic
acids and other dissolved organic compounds. I suspect they acclimate
well to the slightly higher general hardness quite easily. For
breeding, I understand, you want cold, very soft water.

Thanks for the nitrification & denitrification info George. This
is great material. Graphic proof while a lot of labile ( decomposable) 
material in your substrate is not a good plan.


> From: Chazz Hesselein <maf01562 at maf_mobile.al.us>
> The last week of November I set up a 75 gallon, heavily planted, tank.  I 
> work at a horticulture experiment station and have access to many 
> different fertilizers.  One of our best fertilizers is the brand 
> Nutricote.  I decided I would add some 360 day, slow release formulation 
> to my gravel as if I were planting a terestrial plant.  The result of 
> this decision is that my ammonia levels are always up over 7ppm, however 
> my fish haven't shown any signs of stress yet.  Algae hasn't been too 
> bad, yet; I've got 10 SAE's, 5 otocinclus and 1 clown pl*co.  I've tried 
> vaccuuming the fertilizer out of the gravel with my python but it doesn't 
> provide enough suction to pull the fertilizer prills out of the tank.  
> I'm thinking of attaching my gravel cleaner to my Magnum 350 to see if it 
> will create enough of a vaccuum to pull the prills out of the aquarium.  
> Any other suggestions?  My plants are all looking great but if I can't 
> remove a goodly amount of the fertilizer I think I'm stuck with frequent 
> H2O changes to keep my ammonia and phosphate levels down and my pH up.

Chazz described a gravel substrate with slow release fertilizer prills
in it which has been stirred up thoroughly with a gravel cleaning
vacuum. Ammonia is consistently over 7ppm however the fish aren't
dying (yet).

I suspect that these prills contain a very concentrated fertilizer
and that the slow release of nutrients which you might expect in
terrestrial application is not happening. Instead, being dissolved
under water is drawing the nutrients out very rapidly. Chazz, you
might be able to lower ammonia levels by instituting heavy 
biological filtration. That's going to produce extremely high levels
of nitrate which aren't too great but aren't nearly as toxic to fish
as ammonia. I don't expect that you are going to be able to change
this situation by water changes or gravel washing or filtration.
Probably the best thing to do is set up another aquarium if you
have one with clean water, a filter and some of your aquarium water.
Put some of your floating plants in it and a light and transfer
your fish out while you remove your old substrate. Take care when
moving the fish as your pH has probably crashed and you undoubtedly
have high nitrates by now.

I'm somewhat familiar with your situation. :%]

Steve      in Vancouver growing lots of Daphnia with my green water.