Substrate testing at UC Davis

[Tom Barr]

I am going to do some lab managing at UC Davis' Aquatic plant research lab soon. This job has many advantages as it allows us to do many controlled experiements to answer questions.

Substrate speculations run rampent on the web. I've fully addressed water column issues thus far.

What I will be able to do now with their facility is to see about different substrate's impacts on aquatic plant growth. The system involves a series of 500 gallon tanks with controlled light, but a RO/DI water source that removes everything from the water column.

Therefore the plants must use only the substrate alone. We use 8" pots for this and have room for many plants. I will use a weed, Eurasian milfoil(M spicatum) as it's a weed of interest in the USA/CA and fast growing. I plan on adding a few pots of ADA, Florabase, Onyx, Flourite, EC, Sand laterite, etc to see about culture. Relative growth rates are used to estimate biomass differences and we have that data for the dry weights already.

So by knowning the dry weights of the plants after say 8 weeks, we should be able to see over this time frame, which performs better. If we chose to use it longer, I'd need to do the test for months, years etc.

The other option would be to use some ADA/Onyx ewtc that has been used for a 1 year etc and compare those over an 8 week peroid.

While there is enormous speculation about substrates and their influences, the BarrReport will find ways to answer them in a controlled manner. I'm tired of sales pitches. Most folks are. I'm tired of folks asking to "believe in them" and trust this product over a long peroid of time.

Science can answer those questions. Spiritual matters are not my area of expertise so I do not answer those questions

I plan on using the native CA Echinorodus as well later.

Regards,

Tom Barr

 

[Bill]

Re: Substrate testing at UC Davis

Hi Tom,

I have a question regarding substrate. My 120g tank started out as a african cichlid tank and has gradually evolved to a planted tank. While I still keep a few smaller africans cichlids most of my other fish are more along the line of your normal planted tank fish.

My question on substrate is this, I have recently changed my CO2 reactor from internal to external and moved and replaced alot of plants. I am now using your EI and I am hoping for good results. My substrate originating from the fish tank period is Aragonite. While I have had success growing plants in this in the past I was curious to know if you think I should pull it all out and replace it with a more plant friendly substrate?

Here is a link to the specs I have found on Aragonite http://www.purearagonite.com/facts.html

The only difference between the aragonite in this link and what I have is the size, mine is about the same size as Flourite.

Thanks,

Bill

 

[Tom Barr]

Re: Substrate testing at UC Davis

Did you see the images of the larger 250 gal planted Tangy tank?

That's aragonite. CaCO3. So is onyx sand, it has some more Fe in it and it's calcite, a little bit lower solubility than the aragonite form(orthrhombic).


I'd leave it, keep the AF rift fish switch to Juli's, Lamps, Syno cats etc.

Get into the rock work and planting both.

Otherwise, go all plant and use onyx sand, or use onyx sand for the Rift fish.

1) leave it and add Fe to the substrate

2) remove it, add Onyx sand or other preferred brand

Regards,

Tom Barr

 

[Bill]

Re: Substrate testing at UC Davis

Hi Tom,


I will stay with the aragonite as you suggested but is there a type of Fe that I can add to the substrate that would still have the white color look like the aragonite?


If not, is there a problem just adding Fe to the water and not the substrate?


Thanks,


Bill VanHorn

 

[Tom Barr]

Re: Substrate testing at UC Davis

You can place white iron rich clay etc or laterite balls etc in there. Seachem's tabs would work as well.

Yuo can add just to the water column also, some plants, only a few will need some iron in the substrate though to look good. They will still grow etc, but not as nice.

Regards,

Tom Barr

 

[jerime]

Re: Substrate testing at UC Davis

Hi Tom,
Can you tell me if dolomite (2-3 m"m size granule not the powder for ph balance) can be used safely as substrate (instead of quartz). Is it inert?
Thanks.

 

[Laith]

Re: Substrate testing at UC Davis

I wouldn't think so. Dolomite is Calcium and Magnesium.

It is not inert in the sense that it will dissolve. It may take a while, but it will leach Calcium and Magnesium into your water.

 

[aquabillpers]

Re: Substrate testing at UC Davis

When I read Tom's original posting I looked forward to the publishing of the results. And I still do.

But now I have a question. The purpose of the experiment is to see which of the substrates produces the most growth in an otherwise nutrient-free environment. And that is good.

But since M. spicatum (and most if not all other aquatic plants) supposedly get their nutrients from the water column, I wonder what the plant keeper can conclude from the experiment. If Substrate A produces the most growth in the test environment, how would it and the other substrates compare in a more normal environment in which there were adequate nutrients in the water column? Would there be any significant difference? That would make a more interesting experiment, IMHO.

Bill

 

[Tom Barr]

Re: Substrate testing at UC Davis

It will show the relative differences in terms of nutrient supply from the substrate(only for the time peroid of the test).

Soil does pretty good over a few weeks time frame, so will a few of them that have nutrients added.

But all the high techers seem to believe there is something magical in ADA substrates rather than a source of macro nutrients like soil.

Nutrients like macros run out or diffuse out after a few months, at that point, you either need to be aware of this and repsond or else the tank will dip into a stalled growth peroid and likely get algae if not enough nutrients are being supplied.

A good reason not to add merely just enough......always add more than the plants need.

That way you will not be caught whether you use an enriched substrate for macros or not.

Amano gets around this by adding different nutrients after a certain amount of time has passed (after all the nutrients run out in the substrate).
Brighty K after 3 months , Special Z after 6 months etc....

So he knows they run out and you need to add more to the water column or replace the substrate.

Amano may not have developed the products also, he might have had some else do that for him. From what he has said, that seems to be the case.

Is adding anything to the substrate helpful?
For some folks it might be.

But they will need to dose later at some point.

Regards,
Tom Barr

 

[Stu]

Re: Substrate testing at UC Davis

Look forward to seeing these results!

Tom, have you seen this product.... PLANT GROWER BED?

It's claim are some of the strongest I've seen to sell a substrate...
"keeps the water pH value between 6.5-6.8", "Suppress algae", "Suitable for microorganism", "purify water quality", "extend the water exchange time", and my favourite... "the best substrate for the aquatic plants"

It's also one of the most costly substrates I've ever seen, and needs replacing at 18 months.

 

[andrewmcleod]

Re: Substrate testing at UC Davis

From the link above...
"All aquatic plants need under gravel to root and grow. The water and minerals from the gravel are absorbed to the xylem in vascular bundle through root hair, and then transmit to stem and leaves. Thus, chloroplast can process photosynthesis to produce oxygen. Therefore, the gravel concerns the growth of aquatic plants. So a fitting and proper gravel is really important for the aquatic plants."

Erm... isn't that what plants which AREN'T underwater do? Why the hell would an aquatic plant need to take water from the roots to the leaves?

 

[happychem]

Re: Substrate testing at UC Davis

Definitely looking forward to the results.

One question came to mind though...

If the pots with the plants are in the same tank, is there likely to be any significant effect of nutrients dissolving into the water column from one substrate and enhancing the growth of a plant in a poorer substrate?

 

[Tom Barr]

Re: Substrate testing at UC Davis

Anything that grows aquatic plants does all that, adding nutrients does that, I have non CO2 planted tanks without a water change now going on 6 months in my new place in CA.

You can say the same thing about using soil in a non CO2 plant tank, or adding water sprite to a tank without any gravel.

I do not really see anything that has not been said before by substrate sellers.

It does not hurt, but it also does not do everything they claim either......

Regards,
Tom Barr

 

[aquabillpers]

Re: Substrate testing at UC Davis

It does not hurt, but it also does not do everything they claim either......

The only things that get hurt are the wallets of those who buy that stuff.

Bill

 

[Tom Barr]

Re: Substrate testing at UC Davis

Well, it depends...........some folks do not fertilize their water column at all.
These folks will have better luck with this product than nothing.

Regards,
Tom Barr

 

[aquabillpers]

Re: Substrate testing at UC Davis

Well, it depends...........some folks do not fertilize their water column at all.
These folks will have better luck with this product than nothing.

OK, but why? You've said that some of the special substrates provide more surface area and that causes a more efficient distribution of water column nutrients, and that's reasonable, particularly when compared to fine "playbox" sand, which permits little water movement into the substrate. But more surface area/permeability than 2mm - 3mm gravel?

Some of these special substrates leach iron into the water and that can be useful (sometimes), and some disolve, adding hardness that can also help (sometimes). But do any add nitrates or phosphates? And if any did, would you want that?

Soil tanks can add all of those things, at least for a while, but that substrate has its own drawbacks. At least it's cheap. I'm now thinkling that an ideal substrate might be gravel with water column fertilization, thanks to a great extent to your teaching. I'll know better when my current experiments have been completed. (I know, they are not necessary )

My main concern in all of this is that inexperienced people spend hundreds of dollars on a special substrates because so many people gave it rave reviews, and end up with a lot of dead plants because they didn't do much else.

Bill

 

[Tom Barr]

Re: Substrate testing at UC Davis

OK, but why? You've said that some of the special substrates provide more surface area and that causes a more efficient distribution of water column nutrients, and that's reasonable, particularly when compared to fine "playbox" sand, which permits little water movement into the substrate. But more surface area/permeability than 2mm - 3mm gravel?

Yes, much more, 2-3mm gravel has no internal spaces, the anaerobic bacteria die anytime you disturb the substrate.
Not so with high surface area grains.

But do any add nitrates or phosphates? And if any did, would you want that?

ADA's has NH4, soil obviously has these as well as do manures.

Soil tanks can add all of those things, at least for a while, but that substrate has its own drawbacks. At least it's cheap. I'm now thinkling that an ideal substrate might be gravel with water column fertilization, thanks to a great extent to your teaching. I'll know better when my current experiments have been completed. (I know, they are not necessary )

My main concern in all of this is that inexperienced people spend hundreds of dollars on a special substrates because so many people gave it rave reviews, and end up with a lot of dead plants because they didn't do much else.

Bill

Well, new folks are always prey to these situations.
You are precisely correct though about that.
Rave reviews without discussing the other issues(oftne the folks raving do not want to critize anything or suggest other reasons for the success and never do controlled test) always causes issues.

One thing does not magically grow plants.
Folks have done the substrate sales pitches for many years, folks have spent 400-600$ for heating cables until I finally beat it into folk's heads, they really do not do anything.

This at least adds some nutrients.
But so does soil..........

Which is a big point of Diana Walstad's and rightly so.
That's more "natural" than these products.
Not that's better, but folks always like to use that term, without knowing much about it.

Regards,
Tom Barr

 

[aquabillpers]

Re: Substrate testing at UC Davis

Yes, much more, 2-3mm gravel has no internal spaces, the anaerobic bacteria die anytime you disturb the substrate.
Not so with high surface area grains.

Thank you for your responses. They make a lot of sense to me, now.

Just one follow-up? We might be talking about different things. The substrate that I am talking about is quartz or silica, made up of irregular 2mm -3mm pieces, and called "builders' sand" or "blastiing sand" in some areas. Water flows through it quite rapidly. That suggests that it doesn't "pack" and thereore has a lot of surface area.

I just filled a 12 ounce water glass with that gravel, and i was able to add 8 ounces of water (by volume) to it before it overflowed. There was virtually no pause between the addition of the water and its disappearance. That suggests that it doesn't "pack" and thereore has a lot of available surface area for the little buggies to roost on.

Bill

 

[srozell]

Re: Substrate testing at UC Davis

From what I've read here, I understand that Onyx Sand (Seachem's product) is currently the substrate of choice for tank using the EI approach and CO2.

Is this assumption correct? It matters currently as I'm setting up another 20 tanks, and I want to get as close to perfect as I can first try on these ones.

Also, is there a cheaper version of Onyx sand? Is this something I can order by a different name by the tonne for the same money?

 

[happychem]

Re: Substrate testing at UC Davis

Anything that grows aquatic plants does all that, adding nutrients does that, I have non CO2 planted tanks without a water change now going on 6 months in my new place in CA.

You can say the same thing about using soil in a non CO2 plant tank, or adding water sprite to a tank without any gravel.

I do not really see anything that has not been said before by substrate sellers.

It does not hurt, but it also does not do everything they claim either......

Regards,
Tom Barr

Actually, what I was asking was a crossover effect likely:
Let's say that there's substrates A and B
A is plain silica sand, it offers no nutrients so in theory the plants would grow slowly on stored nutrients then die in time.
B is contains plenty of nutrients so alone the plants should grow well, at least these are the hypotheses.

But since they're both in the same tank it's conceivable that nutrients from B dissolve in the water and nourish plants in the pot containing substrate A. One possible outcome being that both plants grow at the same rate. So on measuring the dry weights after x time one would conclude that neither substrate is superior in terms of growing plants, but in reality the growth rate of plants in pot A was entirely due to nutrients from substrate B.

I don't know if this is a likely and was wondering if you thought it may be. What can I say, I like research and experiments.