[MarkM]

I have two low tech planted tanks. Each has a medium fish loading, medium to heavy plant load, low light, reasonable filtration, substrate, and temperature. Plants are all low light and are growing OK, though slow. Algae is under control. I am dosing with the dry ferts specd in PPS as below but once a week or 10 days not daily as that program is for CO2 and high light.

K2SO4 potassium sulfate
KNO3 potassium nitrate
KH2PO4 potassium phosphate
MgSO4 magnesium sulfate

I have to perform a 50% water change each week to keep my nitrate level in check, under 20. I assume that my plants are not using the nitrates produced by the bio load and that my dosing additional KNO3 is putting too much nitrate in the mix. Should I reduce or eliminate the KNO3 in my fert mix?

thanks,
Mark

 

[ForensicFish]

What are your tank sizes? What/how often do you feed?

If your plants are doing well and Algae is under control I see no reason to deviate from your current dosing regime.

However, if you are tired of doing 50% weekly water changes I would recommend reducing your dosing regime across the board. If you just reduce one and still the overabundance of others you can cause algae. Your low light plants are not going to consume the nitrates at a rate where you constantly have to dose to replace them.

In my opinion, you could easily stop dosing at all. Your fish load, feedings and say weekly water changes would do just fine. Just my opinion.

What do you currently have for lighting? Photoperiod? Plant species?

All of this would give the people here a much better perspective on your current setup to lend a helping suggestion.

Unfortunately dosing is trial and error. You seem to have a good gauge on how your tank is performing now with your current dosing regime. I don't think anyone on this forum can accurately tell you how much to reduce your dosing. Just reduce them all bit by bit and observe your results.

 

[THE V]

+1 dosing a low tech tank is all about trial and error. Also remember that plants have a growth curve. Their nutrient uptake matches their growth. In time they will require more and more as their biomass increases.

I notice that you are not adding in any general trace blend other than Mg. Perhaps the plants are not consuming as much of the macros due to the limiting of some of these. Not enough to show deficiency but enough to slow them down.

 

[MarkM]

More Info

OK, more information on my tanks. First I have a 120 and a 50. Fifty has been up for about 9 years with plants for about 1 year. The 120 has been up for 8 months.

Here are picts of the 120 and 50.

Both tanks have LED lighting set a a Par level of 20-25 at the substrate. The 120 gets light for 8.5 hours a day and the 50 for 7.5 hours a day. I do dose with TE once a week at the same time as the macros. I have been using the base PPS formula which provides an ingredient amount of each element to dose on a daily basis. As I am low tech I expect slow growth and I cut the frequency to once a week or ten days from daily but kept the mix the same.

In terms of plant names, I am lost beyond wisteria, madagascar lace, anubias, java ferns. I do have about a dozen other plant types.

Fish load is I believe medium. 120 with six juvi Angles, a dozen Tetras, and four Corys. The 50 has 18 Tetras and 3 Corys.

Mark

 

[roadmaster]

Could prolly do away with the K2SO4 for there is plenty of potassium in KNO3,KH2PO4.
Would not worry about reducing KNO3 for it would take many ,many ,more PPM to have negative effect on fishes.
Last time I checked Nitrate level's in my own low tech tank's the ppm were around 80ppm.(I dose nutrient's once a week also)
Plant's ,shrimp's,fishes,are thriving so I put away the test kit.
I simply perform weekly 50% water change and redose.
P.S. I think your plant's look great.

 

[Diana]

If you want to do less water changes (smaller volume, for example) then yes, use less KNO3.
Also, use less KH2PO4. Fish food supplies reasonable amounts of N and P.
But I would not reduce the K2SO4. When you reduce the KNO3 that will reduce the potassium. Fish food is not a good source of potassium.

What is the GH of the tap water?
GH measures Calcium and Magnesium.
Plants use Ca and Mg in a ratio of about 4 parts Ca to 1 part Mg.
It is good to have water with more or less about that ratio.

If the tap water has a GH of at least 3 German degrees of hardness, then you can assume there is enough Ca and Mg for the plants. If you see some problems, then you can do separate tests and figure out what you need (Ca by itself, Mg by itself or a combination).
I would not dose Mg by itself without making sure that is what the tank needs. Too many fertilizer companies sell people magnesium when they do not need it. Epsom salt is cheap. But it is not a complete GH booster. It has not calcium.

 

[roadmaster]

If you want to do less water changes (smaller volume, for example) then yes, use less KNO3.
Also, use less KH2PO4. Fish food supplies reasonable amounts of N and P.
But I would not reduce the K2SO4. When you reduce the KNO3 that will reduce the potassium. Fish food is not a good source of potassium.

What is the GH of the tap water?
GH measures Calcium and Magnesium.
Plants use Ca and Mg in a ratio of about 4 parts Ca to 1 part Mg.
It is good to have water with more or less about that ratio.

If the tap water has a GH of at least 3 German degrees of hardness, then you can assume there is enough Ca and Mg for the plants. If you see some problems, then you can do separate tests and figure out what you need (Ca by itself, Mg by itself or a combination).
I would not dose Mg by itself without making sure that is what the tank needs. Too many fertilizer companies sell people magnesium when they do not need it. Epsom salt is cheap. But it is not a complete GH booster. It has not calcium.

GH test's do not tell you whether the reading rendered is comprised of mostly calcium,or magnesium without specific testing for both.
Why wait until deficiencies appear, when you can add a little of everything that plant's need? Nutrient's in the way of mineral salt's are not the boogey man.
Might read up on how important magnesium is to plant growth.
Also would not rely on fish food ,fish waste,for KNO3 and phosphates for everyones stocking,feeding's, types of food and their content,are often different.You would be just guessing in my view.
Also as plant mass increases,the plant's may very well use more of everything so EI dosing ,or scaled back version for low tech, is much more productive than trying to limit this or that nutrient, at least until such time as you are able to readily recognize what plant's are trying to tell you.
If you are dosing KNO3,and KH2PO4,then as mentioned,,you do not need the K2SO4 but it does no harm to add it either.
Water changes are entirely up to whoever is performing them but for me,,If I've already got the hose out ,python,bucket's, then 50 % water change is just as easy as smaller water changes and plant's and fishes will thank you.