What is my deficiency - tiny leaves

[jsoong]

I must be having some kind of deficiency - all my plants (except hornwort) are getting smaller instead of bigger!

The Cockscrew Vals started out with 6-8" long leaves, but in my tank, the leaves are only 1-2". They are reasonably happy tho, since they have sent out runners like mad & I now have 30 or 40 plants covering 1/3 of the tank, but all are 1-2" tall.

Ditto for Hygros .... old leaves fell off after planting, and new ones are only 1/2" big (1/4 the size of the originals). They are also not growing too tall (5-6"), but are spreading like weeds sideways.

Anubias nana - leaves 1/8" .... Java fern, 2" leaves .... the list goes on.

All except the hornwort .... my little bunch had taken over half the tank, and is growing at least 1-2" a day. I routinely throw out 1/2 of the plant mass each week.

Some specs: 75 gal, 4x32W T8, Profile (Schultz aquatic soil) substrate, no CO2, dosing 5ppm NO3, 5ppm K, 1ppm P & 0.1ppm Fe (& trace) weekly ... change water 10-20% weekly (doing less on advice that low tech tank should have NO water change ... but I just can't stand the mess the goldies make, and my NO3 keeep bottoming out so I have to dose or I get BBA).

So what is the problem? I suppose I can use the vals as a carpet - looks kinda cute at 1" tall ... but I would like to have SOME tall plants for background instead of just a big bunch of hornwort .....

 

[travis simonson]

Nitrate deficiency can cause some plants to put out smaller than normal leaves so you may want to test it over the course of the week to see if it is dropping below 10 ppm or so. Do you see any yellowing of mature leaves?

 

[jsoong]

Well, the NO3 is always low ... I guess the hornwort is soaking up ferts as fast as they are added. Rarely is the NO3 over 5, if I don't add KNO3, it will bottom out to 0 within 2-3 days. ... And no yellow leaves ... Although the "original leaves" from when I first got the plants had long since fallen off, the new "mini" ones seems to be green & healthy.

If the hornwort is out-competing everything else for nutrients, I would expect the others to have stunted growth. What I don't understand is why there appears to be lots of growth - runners, sideshoots, etc - but all with mini sized leaves. The Vals must have triple the biomass or more since I got them ... with all the baby plants growing everywhere. If there is a NO3 deficiency, shouldn't there be low or no increase in plant mass?

I am now trying some root ferts - since they should not be taken up by the hornwort, maybe this will make some difference.