Questions about diy dry fertilizer

[Evathys]

I am growing various species or cryptocorne, java fern, and vallisneria in a 55 gallon tank with various somewhat soft water fish. I have done a lot of research online but I still can’t find answers to a few of my questions. Will dosing nitrates be harmful to fish? Will sulfate or pure sulfur cause any problems for fish, plants, or water quality? And finally, I bought my tank used and therefore have no info on the light specs, it’s florescent but other than that idk. Will this be ok or do I need a new light?

Btw I’m using ro water, use 1-3mm gravel as substrate, have flourish root tabs in place, will be doing weekly 20% water changes exchanging old water with fertilized water, and my plan for remineralizing/fertilizing per liter of new water is:
KH2PO4 - 2mg - 0.5ppm K, 1.4ppm PO4
K2SO4 - 22mg - 9.8ppm K, 12.1ppm SO4
CaCO3 - 71mg - 28.4ppm Ca, 41.6ppm CO3
CSM+B - 3mg - 0.2ppm Fe
MgSO4 - 2mg - 0.4ppm Mg, 1.6ppm SO4

(10.3ppm K, 1.4ppm PO4, 28.4ppm Ca, 41.6ppm CO3, 13.7ppm SO4, 0.2ppm Fe, 0.4ppm Mg, 2.8ppm trace)

Thanks for reading that mess

 

[ZxC]

Nothing wrong with dosing KNO3 up to 40ppm weekly, although with small water cahnges like yours it may creep up rather fast.... 50% or more would likely be better.

Your micros won't be very effective if dosed all up front, the Fe will likely precipitate out.

0.4ppm Mg is 10x too low.

Vals really like Ca so I would dose 20ppm Ca from CaSO4.

Extra S isn't going to hurt anything either.

What does the bulb say? Any pics of the lights?

 

[Evathys]

So I looked a little closer at the light and found what is pictured, also were you suggesting 20ppm additional Ca or total?

Would changing my potential dosing schedule help anything? I was planning on mixing the dry chemicals in my new water every wc so I’d really only be adding 20% of a full tank dose every week, my goal isn’t to turn my tank into a greenhouse, I just want to make sure the plants get what they need and the water is remineralized.

You said that the Fe might precipitate, is there any other chemicals that might interact if I add them at the same time? Could I fix the problems by dosing 30% Of a dose of CSM+B every other day?

How much nitrates should I expect my fish to produce? I’m planning on keeping 3 pearl gouramis, 6 kuhli loaches, 9 cherry or fiveband barbs, and 12 lambchop rasboras.

I won’t worry about the sulfur so thanks for the tip. Should I aim for 4ppm Mg?

If I were to not dose nitrate or just dose in small amounts would I be able to keep a 20% weekly water change?

Thanks! I appreciate any and all help given

 

[ZxC]

How many bulbs are you running? 55 gal tank?

What is typically done when remineralizing RO (got planted tank) is the addition of Ca, Mg and CO3-2.

To do this you would add CaSO4 (for Ca), MgSO4 (for Mg) and some sort of carbonate.

Working with these values I would recommend the following:

Dose gH (general hardness or Ca+Mg) to 8dgH. Use a 3 or 4 :1 ratio of Ca to Mg.

Dose kH up to 3dkH.

Rotalabutterfly is a nutrient calculator that you can play with to help find values.

For example, my personal tank uses a mix of hard tap water : RO water at a 1:5 ratio.

I then gH boost using CaSO4 and MgSO4 another few dgH, 4 ppm Mg and 16 ppm Ca (4:1 ratio of Ca:Mg). This plus my hard tap water in my mix gives me 8dgH.

I don’t dose any kH (carbonate hardness) because the 1:5 ratio of hard tap: RO water gives me 3dkH.

I would not dose fertilizers to the new water. Just remineralize Ca, Mg and carbonate.

Use the rotalabutterfly calculator to determine how much fertilizers you will need to reach certain values, and which coming dosing regime to use.

With my water parameters mentioned above, my degrades pH is 7.6, and with CO2 it drops to 6.6 during the photoperiod.

CSM+B is best effective a pH of around 6.5. I would use 50% of your total dose using CSM+B and the other 50% with flourish comprehensive. Again use rotalabutterfly calculator to help determine ppm values of each

 

[Evathys]

Thanks for such a detailed response!

I have just the one 36” bulb in my 55gal(36”,18”,21”)

I’ll play around with the calculator you mentioned to find a dosing routine that will work for me.

So the goal is 4:1 Ca:Mg, ~30ppm NO3, ~10ppm K, ~1ppm PO4, and >4ppm mg?

The only concern I have left is the tds, which I would like to maintain near 6dh. Is this reasonable or just an unnecessary precaution for soft water fish?

 

[ZxC]

With the one bulb very low light plants would work best. Java fern, anubias and java moss for example. Run a bulb with a 3000 through 6500 kelvin (or K rating) for maximum PAR. 2 bulbs would be best.... for low light anyway. Expect very slow growth with the 1 bulb. A glut source such as flourish excel should be used to help with potential algae build up on older leaves because of the slow growth.

With my mix I end up with:

8 degrees gH
3 - 4 degrees kH

**** for reference, this mix ends up with a TDS of 145ppm. If you are after softer water you can cut it back to 2 degrees kH and 5-6 degrees gH. This should result in soft water and “enough” Ca and Mg for plants. Any plant I have grown will work in parameters like this.

You can probably cut back the Ca and Mg in the remineralized water if you plan on dosing CaSO4 and MgSO4 through the week. Just watch the potential “creep” with smaller (20%) water changes.

Ideal is NO3O4 is around 5 - 10 : 1. So for every 10ppm of NO3 you’ll want 1-2ppm PO4.

Potassium can be equal if not more than NO3.... as far as I can tell it will work.