Re: Aquatic Plants Digest V2 #209
> Subject: Please Help Me (I am in trouble)
> I have a strange situation. I have recently set up a 55 gallon
> freshwater plant tank. I have a soil/vermiculite/peat substrate covered
> with gravel. The problem is that my PH is very high (8.0-8.5). My tap
> water is extremely hard and has a 7.5 PH. I cannot discover why my PH is
> so high. I origionally thought that the gravel that I bought contained
> marble chips (I tested it and it had a PH above 9). I then removed
> almost all of the old gravel and replaced it with new gravel (without
> marble chips). I left the old soil in the tank and put the new gravel on
> top of it. Now the PH constantly increases to 8.2 or more. Even when I
> adjust the PH down, it raises again.
What makes you think your new gravel is any less alkaline than your old
gravel? How hard is your tap water (as both total hardness and 'temporary
hardness' or alkalinity)? Is your tap water pH 7.5 ... thats not exactly
clear. You replaced 'almost' all of the old gravel? ... perhaps you
should have been more thorough. Have you tested the pH of your soil
mixture? Did you do a complete water change when you replaced the old gravel?
> Since my PH is raising to 8 or more isn't the buffering effect of the
> water exhausted? Why would it still increase?
No. As the pH increases, the buffering capacity also increases since it
is largely the alkalinity (as bicarbonate) that both buffers the water
and increases the pH.
> Please help me. I am on the verge of tearing down the tank and removing
> my soil mixture and cleaning my gravel.
No, you dont need to do this. I think you last comment is instructive ...
let you plants guide you as to what needs to be done... if they are happy
then there is really no problem. One of the interesting side effects of
high pH is that the amount of inorganic Carbon in the water increases
dramatically (as bicarbonate). Plants that are able to utilize
bicarbonate will grow great and CO2 injection becomes totally unnecessary
(which IMHO it is anyways).
You should check your new gravel by dropping some vinegar on it. If it
fizzes then it will increase the pH of your water. Also check the soil
that you used. If the tap water is lower in alkalinity and pH than your
tank water, then frequent water changes are in order. Whatever you do,
stay away from pH Down or any chemicals of that ilk ... they are almost
exactly the worst possible strategy for altering the pH of your tank.
Finally, if your tap water is hard and alkaline, then you may want to
consider RO or distilled water as a means of reducing your pH.
> PS My plants are having a great time.
> From: jphealy at sysconn_com
> Date: Fri, 20 Sep 1996 13:34:10 -0400 (EDT)
> Subject: Re: Aquatic Plants Digest V2 #208
> > When trimming back my plants, I've often considered leaving the
> >trimmings in the tank and letting them degrade. Although this would not
> >make the tank look more attractive, I figure I would be allowing the
> >release of iron (and other nutrients) from the decaying plant matter.
> >Hence, the remaining plants could benefit from this slow, sustained
> >release of nutrients.
> > I'm sure that I will still have to add iron and trace elements, but I
> >shouldn't have to add them as often. As long as my filters can handle
> >the extra bioload of decaying organics, I can't see any problems
> >arising. Can any of you?
I dont think this is a good idea simply because of the release of
phosphates as the leaves decay ... increased P levels are a sure method
of getting algal blooms. Bacterial blooms are also a possibility as the
organic matter content on the tank increases. There is also some research
to suggest that decaying plant matter possesses allellopathic properties
in that it can reduce growth of exposed plants.