I get along with engineers and understand them because I almost became one. I often get into debates over the biological aspects in aquatic ecosystems with them.
I am not addressing you or anyone in particular, I think many newer folks do not know my history using substrates and the other folks in the past. It was
the method way back when. I did a lot of work on substrate back in the 1980's and 1990's.
Some have said that the water method is old hat, that rich substrates are the all the rage today, heck, most simply do not have access to KNO3, but jobes, boiling(which removes the NH4/Urea) worm castings, manure, chicken crap etc all have the same elements and uses for plants. These have been used since at least the 1960's in planted tanks. I can assure folks, this ain't new.
What I am pointing out is that the water column does not need to be limited, this was/is a myth. That is new in the plant tank hobby.
It's not new in research though, PO4 and NO3 are used as eutrophic indicators to some degree, but when you add plants in a shallow lake, even with high PO4/NO3, if there is roughly 30-50% or more substrate coverage by plants, the water will be gin clear, if you removce the plants, the lake will turn to pea soup.
Most studies looked at northern lakes, since most researchers tended to be bais to their location of institutions rather than tropical or subtropical lakes that do not freeze and have stable long term plant populations.
Other assumptions like taking into account the amount PO4 locked up in the plants when testing the water column were also not taken into account, see Phillips 1978, which did not adress that, but used the water samples that had the algae's PO4 taken into account.
Suddenly there is no pattern that relates algae to eutrophic waters, eg an R^2 value of .10 when you sample the PO4 in the plants, vs an R^2 value
of close .82 without that critical piece of sampling information.
The paper was bias towards the algae. It's been cited some 300+ times also, so it's gotten all around, but many lakes don't have plants or only a very few around the edges in the littoral zones, so then the papers are generally correct.
Few look at plants vs algae. They mainly look at algae, so there's that bias as well. There has been far more research done on algae than aquatic plants also, so there's even more bias in the literature.
Additionally, emergent plants do not have the same issues as submersed plants and many wetland plants are emergents, so there's even more bias.
So these are few reasons why folks say the NO3 and PO4 cause algae in a planted tank.
Back to the substrate:
If worms is all ya got, you have to work with it. If you have more materials to test with and try out, then you can compare the two.
You can force any method as long as there is a supply of nutrients for the plants for a given rate. But over time folks settle into a routine that works for them. I hope you plan to take a vacation some day and can leave the tank for a little while
Thanks for the overview of the tank, looks nice.
An aquascaping notion: You might try extending the log upwards at angle and try and cultivate the moss on the wood more and keep it trimmed down low but not remove any that spreads as it attaches to the wood.
Wood is extremely non labile as far as nutrients good. Moss is not going to derive anything in an aquatic environment from the wood realitsically.
You'll find moss mainly growing on rocks and stable substrates(sometimes logs but this is more rare unless they are very large or along the banks on living or dead stumps), not wood preferencially.
Moss will be found in generally cooler waters rich in CO2/GH.
The moss does not look like it should really but is growing. Moss will "ball out" when it is growing well and has been in a good environment for awhile(several weeks). How old is the tank?
I think a bit later you will want to try and experiement with dose KNO3/KH2PO4 vs jobes.
But you can continue the method since a tear down and redoing the substrate would not be tough.
The other thing you can do, add the jobs to the plenum, that's what I would do personally.
This would prevent uprooting..........ahhhh......
It would keep that nutrient rich layer away from disturbances and still provide some exchange.
The jobes generally will be fine..........until you uproot, but I know the key element here why they are NOT presenting an algae bloom, even if you uproot, you do daily water changes so the NH4, not the NO3/PO4 etc is being removed before it has a chance to induce the algae spores which are certainly there and present.
The inducement takes about 30 hours on average with NH4 present in the water column. The levels are very low for NH4.
When people do large prunings, I always suggest they clean the filter/prune first, net out any 3excess mulm/dead plant leaves etc.
Then do a large water change.
You can dose back the nutrients to the water column or leave them in the substrate, either way the plants will have access to them.
But since you are doing the large daily water changes, something few people would be willing to do and you might not want to keep up after a few months/weeks/years, you can get away with little to no effect of the NH4.
I think you would be very hard pressed to show a preference in a tank for NH4 over NO3, in control cases with some plants, this is true, but most Ag crops prefer NO3 over NH4. Rice, a wetland plant is the one exception.
If you did weekly water changes, say 50-60% etc, I think you might find some algae creeping in here and there.
If you did a replant, then no water change, I'd bet a nickle you'd get an algae bloom.
If you added some KH2PO4, say 1ppm, I'd bet you would not get an algae bloom.
But that would drive the N uptake higher.
Fish food is higher relative to the plant's needs in N, so fish food will generally limit the PO4 in a tank if that's your only input.
The issue I'm trying to suggest here mainly is one of control and dosing.
While substrates do and can work and we generally all use them to some rleative amount, dosing the water column is generally an easier more stable method.
It requires more consistancy than substrate dosing but prevents issues from occuring and you can test and know what's in your water vs guessing what's left in the substrate after a few months.
Our habits are very much at play when gauging a method.
A non CO2 tank is very easy and nice and relies on the substrate, but the uptake rate from the substrate is limited by light and CO2.
The loading rate(fish waste/water change inputs/plant decay/leeching) and uptake rate of the plants are the elements that need balanced.
It's a fairly easy 2 box model.
All in all, you might want to see about a simplfied method of water changes or automate a small float switch and timer set up for slow water changes at night, with a carbon prefilter for Cl removal.
The other thing I'd suggest you try, after 6 months etc or when you need to re enrich the substrate, try adding the sticks to the plenum layer, actually you can do this with that down spout you use for dosing the traces so you might not need to remove it.
Adding the traces there I do not think will do much either way. You can try this and see for your self.
You can also try adding the KNO3 or KH2PO4 to the water column as well.
You need not worry, you will reset the tank when? Tomorrow?
So the tank will be re set each day..........
So you can experiement around.
Just don't get too many jobes sticks floating around in there.
You'll be dealing with green water then. A UV might help you later if this occurs.
So there's some thoughts to go after and try out here.
I'm not suggesting to you to change your method here, just try some things out to prove to yourself what is really going on.
Each method has something to teach you.
This will help you become a better grower and know why algae was an issue in the past.
It's not a big deal really, it's a small tank and can be reworked if you make a mistake, but try to be careful when you experiement.
Ultimately, I think you will tire of daily water changes though, so I will suggest that change
Regards,
Tom Barr
