The other issue is that NH4 vs NO3 are huge.
NH4 is produced from fish waste.
Eventually it can become NO3 with a good active biofilter.

We do not add NH4(other than some for fish food), we add NO3, which is far less toxic than NH4.

Additionally, with strong active plant growth, plants have the option of using both NH4 and NO3, so they remove all the fish waste, but that's not enough when you use CO2 and decent light.

We still add some NO3 to make sure the plants get enough N.

So the form of N is important.

Anyone that keeps fish only that does 50% weekly water changes has few diseases or issues.

Same with planted tanks, as long as you add the ferts back after.
This keeps anything from building up, or running out.


And since we are slanting things for optimal plant growth and optimal fish health with the lowest amounts of NH4 possible, (Adding NH4 is also a good method to induce various species of algae), things do quite well.

The main thing is to see the difference between NH4 and NO3.
They have very different toxicities and effects on aquariums.

Regards,
Tom Barr

thanks for all the help, especially the plant IDs

Both tanks are getting good growth, the big tank is slower, but still doing well. My lily and val are both going crazy, and the lily is a nice dark red, so that's good. the bacopa in the 90 is getting some new leaves and finally taking root, so I think it will do just fine. There's also new growth on the swords and crypts in there, albeit slower than the lily or the val.

Now, my 90gallon does NOT have CO2 - should I still look at using ferts in there? Or do I really have to get some CO2 running? If I can avoid it, I'd rather not, as, from what I've read, it's too big for a DIY setup, and I am not willing to get into the cost and maintenance of pressurized CO2. As a refresher, I have 136W of HO T5 lighting on that tank.

I picked up a KH GH test kit, and according to that, in the big tank, my GH is 80mg/L and my KH is 40 mg/L. I read everywhere about "degrees hardness" - how do I figure that out? I was surprised about the KH, as my tank water's pH is 7.2, despite a ton of peat moss in the filter, yet my pH out of the tap, and in my goldfish tank, is 7.0. pH in the 10gallon (which has CO2) is 6.4. The pH in the big tank was 7.0 until I added plants, so somehow the plants are making the pH go up in there...

Plants utilize c02 during photosynthesis and c02 will cause a ph drop. The better the growth, the more c02 is used, and thus the ph rises.

That is why the 10 gallon tank's ph is lower than the tap, due to c02.

This is not a scientific explanation, but a layperson's. There is a lot more to this than my statement, and I am sure folks will correct me as needed.

here is a link that will help explain hardness in mg/l vs dh.

Water Hardness

You don't NEED additional c02, but your growth will be slower, less mass, etc. Some plants need more than others...

Depends on a lot of factors............


Hope this helps.

I have a basic (VERY basic, like, highschool chemistry basic, lol) understanding of the relationship between CO2 and pH. i figure that, since I'm not supplementing CO2 in the tank downstairs, the plants are pulling what they can from the water (what's naturally dissolved in there), which is bumping up the pH.

I just tested the KH/GH in my 10 gallon. GH is the same as the 90g (80mg/L), but KH is lower, less than 10mg/L. That I don't understand...

reading the link you provided, I'm wondering if I should be adding some baking soda to my 10gallon?