does anyone knows what causes this in my heteranthera zosterofolia and vallisneria spiralis??

If your Co2 is 30-35ppm. Then I would start by increasing KNo3, and Po4 in that order. Looks like they need a bit of both.

Bevestig: KNo3 & Po4 . Grtz, Prof M

strange, i have tested the water with tetratest(drops) and the no3 was around 25mg/l, po4 with seratest was 1mg/l.
my water from the tap is no3 ; 15mg/l and po4; almost not measurable..
i don't add kno3 because of my testresults and i now add 3times a week about 0.5mg/l po4.if the tests are right it can't be a shortage of no3,po4 can it??

Well, right there you make the assumption that the NO3 test is correct and accurate and you based your dosing on these unknowns.

If you add 3x a week PO4, then you know there's some regardless of a test kit's readings.

However, you do not with respect to NO3.

Also traces and GH and K+ need addressed as well.

You can add these, adding it will not hurt, KNO3 included, even if your test kits are correct.

This way you can rule it out.

IME, Star grass and Vals are fast growers and do better with less light and richer nutrients/good CO2 etc.

Regards,
Tom Barr

The test kit is only as good as the age of the reagents, color scale, and of course the end user. As I recall the color scale on the Tetra test is printed on the box. It's hard enough to maintain the printed color on the packaging let alone keep it dry so it doesn't fade. Now when you factor in that the Cadmium reagent is scooped in by the user, and continuously re-exposed to o2 every single time you open the lid, this introduces a HUGE margin of error ! So unfortunately the Tetra Nitrate test is suspect before you even open the box ! Allowing for the the hygeine of the user, and the square plastic vial (Residual solution, and surface tension of adhesion) The deck is kinda stacked against you. These are splendid, inexpensive test for the avg. hobbiest, but sorely lacking for our purposes.

Short Answer: Sure it could !!! What do the plants tell you ? Grtz, Prof M

i started adding kno3 today(10mg/l) en will add another 5mg/l twice more this week.after that i will add 3 times a week 5mg/l.i hope this will solve my problem.
i also hope that my javamos starts growing than.i have some moss in another tank without co2 ,only excell and there it goes very good with the same watervalues, ph7,kh7,gh14...maybey not 'ideal values for 'all' plants but the ones i now have problems with have done fine for years with the same values.
i am curieus about the result