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COD=> Chemical oxygen demand
BOD => Biological Oxygen demand

Generally COD is quick dirty way to get a measurement wereas BOD takes longer and is a PITA.

Wim and I talked to Amano, we both came away thinking he was not much on the testing/plant phsiology aspect.

I see such consistency in the readings. Every tank is very similar, ...........too similar.

Seems like the test kits or they just tested a few and assumed the rest were the same.

You must also understand that a single reading is just that.
A slice of time, not the same reading throughout the week.

People see one measurement and think that it's some golden level that magically makes everything grow.

But the reality is that these levels change.

Luis, Jared and many others like to change their water 2x a week and if you want nice tanks that jam, that's a good routine. I do it when I want to whip a tank into shape.

Semi auto water changers can be set up to do this also which is what I'll do later with a multi tank set up.

Dosing right after the water change helps and allows all the nutrients to be in the most available inorganic form for the plants.

Other folks enrich their substrates also so they can maintain lower water column nutrients levels in the belief that it might prevent algae more.
I can get good growth either way, but it's simpler and easier for my own routine to use the water column and it's much easier to offer advice with the water column.

Tom Barr

2,069 Posts
Low KH grows better/healthier plants?

Well, I guess the world's leading aquatic botantist have it all wrong? Both Claus and myself have shown otherwise in natural systems. George Bowes and the folks at the Weed Science dept and the Center for Aquatic weed research have show this NOT to be true as well.

I guess we are wrong?
Okay, go ahead and prove it.

Show that George is wrong. That would be very tough.

I'd like to see the paper published. Unless George and many other scientist greatly overlooked some glaring insufficencies, I find this contention without any merit other than speculation at best.

OTOH, a KH of 1-2 is fine, all long as there is sufficent CO2 during the photoperoid. Then the plants will not go after the KH. High KH water will have more carbon available for the plants. You can refer to Bowes' research for further reading. Same for higher pH's. Plants grew better at a pH of 8 than at 5 etc.

I think a KH of 3 and GH of 3 are recommended as a buffer in case they do less water changes, run out for other reasons like low CO2 etc.

But plants do not NEED a Ca level above perhaps 5-10ppm etc, Mg 1-2ppm. But higher levels will not hinder growth either.
I've had Ca level at 400ppm and seen plants grow well in 600ppm Ca levels.

So once again we ask the Limbo Gods: "How low can we go?"

So the low levels go with Amano's approach of "just enough".

There is a range, as long as things do not become limiting, then you will be alright. But for many this is a very narrow range and difficult for new folks to hit.

But trying to explain that is not easy to others, it's based on his experience and imparting that is much harder. And why do that and use RO and go through all that trouble as well when it does not gain you anything? You do not get better growth etc.
It does NOT help with algae.

I do not see anything that suggest it does in nature, in my tanks or others, nor in control lab studies or modeling.

Higher levels allows for user errors more and more wiggle room.
An experienced person with moderate light and good CO2 can play around with this and tweak things slightly to their routine or liking.

We also know that night time aeration is not needed nor is 24/7 CO2 bad either, but Amano does that also.

It might be the sodium or something else you are dealing with, but the hardness itself or the KH is not the issue.

You can do RO for an intellectual experience, but day to day routines are another matter.

I think Edward is referring to an almost "religious" attitude about some things with this hobby. The folks with SFBAAPS often joke about this. "Steve the baptist", "Give me more K+!", "Add more TMG!".

Many assumed PO4 caused algae, "add just enough". Well, the utility of that apporach is much tougher for many folks to hit, it has less flexibilty and relies much more on experience of the aquarist.
Adding excess allows more wiggle room for errors.
Some might see conflict here but as long as the plants have enough relative to light and other paratemeters, things should be fine.

But saying plant prefer soft or hard water, plants need RO and not tap, excess PO4 causes algae etc is not right.
You need to test both sides of the coin. This was not done in the past.
Many seem to think Paul's ACIPA papers was wrong about PO4, but the idea was not to bottom the PO4 out, but rather have it low and not build up, he knows that plants need PO4. "Just enough" was his attitude and approach also, he also used less light than many use today.

More light => less room for error, but you can make up for that some in the substrate if you wish.

Many have said that 0 KH will not work or is bad. Edward seems to have set up a few tanks with low light, perhaps closer to a non CO2 system that works and I have a feeling could be reproduced for example.

But I think many would try and put 5 w/gal of light on it, or crank too much CO2 in there etc and then complain they have dead fish.

There's always a person that hears only _part_ of the story. Then a myth gets going. Thinking about things both directions, too low or too high presents a better understanding.

Many folks that bottomed out the the KH/GH may have been dealing with GH more than the KH in and of it's self.

Still when someone ask me what KH, unless they have some special fish issue and/or are competent, I tell them KH/GH 3.

How low will you go? Play da limbo music and have another shot.

Tom Barr
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