Re: [APD] RE: Acidity and nutrient uptake

["Thomas Barr" <tcbiii at earthlink_net>]

> Diana Walstad's book has some records of experiments she performed on 
> various pH levels and hardness levels.  Basically, all plants prefer high 
> levels of hardness, but a maximum pH of around 8 - I know she did 
> something with low pH as well, but since my water comes out of the tap at 
> pH 8.6, that wasn't relevant for me. 

You can see Bowes et al growth rate work and light max rates with various
pH's.
That paper discusses why the plants do better at higher pH/KH.
pH is not the relevant issue, the HCO3 is..........
High alkalinity water has more total DIC carbon available for plants than
soft water at equilibrium.

This is still a carbon issue and is there enough CO2 or HCO3 available for
the plants. pH is just the ratio of each of these like NH3/NH4 and many of
dissolved species in solution. 

The main issue still gets back to adding enough CO2 or you can add HCO3 is
the plants run out of CO2, which is the case with non CO2 tanks with
moderate light. The non CO2 tank approach does not apply when you are
discussing CO2 enrichment since the system is limited by CO2 and perhaps Co
limited in some regards, but I tested that and found the same results as
the CO2 enriched systems.
I can dose PO4/NO3 to these systems and not have algae as well. I cannot
likely add a great deal since I also do not do any water changes for
months, but I do not need to be very accurate either. Generally the fish
watse produce enough nutrients for most hardy plants, more sensitive ones
need a little additional dosing, weekly or every 2 weeks seems good for
most things. 
.
Plants(and algae for that matter) both prefer CO2, so if you use CO2, add
enough! If you are still having trouble, you need to work on adding enough
CO2, getting that set up correctly.
 
 I add vinegar to my water changes to 
> reduce the initial pH in order to get things to grow - 

All you are doing is temporarily  lowering the pH, converting some of HCO3
to CO2. This does not last long however.
I'll bet you adding Excel will suit your plants and your needs much better. 
Adding CO2 will do even more and be cheaper and easier and give you better
plant growth over the long term.
Adjusting pH/KH can be labor intensive as they need to be measured for each
batch and made up in a separate containers.  
Dosing GH/KNO3/CO2 etc can simply be added as you refill with tap water. 

otherwise the local 
> water will kill even Java Fern and Java Moss - after I started adding 
> vinegar (acetic acid),

Well hehe, you do not do water changes if you do a  non CO2 approach:-)
Leave the tank alone.

If you decide to use an approach stick with the approach. Don't piece some
from one method and mix.
You vary the CO2 levels for only part of the week, plants and algae both
get use and acclimated to low CO2 or high CO2 conditions. 

By doing water changes frequently on a  low CO2 tank with tap
water(generally has high CO2, yours might not), this fools the plants, the
acid might last a day or two longer to give better results than tasp, but
if you set up an experiement, I doubt you'll find the acid vs plain tap
does much. .   

Either way, less work for the non CO2 method and patience, or go with CO2
which is also less work.
Both will result in better plant growth and less work for your routine.

 I started needing to prune my plants instead of 
> having to clean the algae off them - I haven't gotten rid of my algae 
> problems yet, but I'm still trying to fill more of my tank with plants.
> Bill

Well if better plant growth is your goal, you can add CO2 or you go a non
CO2, I'd caution agaionst using acid, it does not add what you need, carbon
for the plants. It'll give you a temp quick fix for CO2 but it does not
last more than a day or so, maybe longer dependening on how much you add.
Acetic acid is produced by bacteria in wet land soils also. It'll break
down.  So the tank might have decent CO2 for 1-2 days and then and rest of
the week be CO2 poor.Tap can do the same thing.

It's a CO2 issue and not one of pH. pH is used to measure the ratios of
species present in the water, but acetic acid is a relatively weak acid and
does not soften the water. Only a strong acid like KNO3, HCL, etc will
accomplish that. I would really suggest you add what the plants need,
rather than doing that. There's a few methods to do that, this can and is
working a little for you, but if you play around I think you'll fine there
are ways to grow the plants better and provide less work for yourself. Of
course, some may not care about that issue. 

Regards, 
Tom Barr  



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