Why harder water = more traces?

I've seen references where you, Tom, says one have to dose more traces in harder water, like http://fins.actwin.com/aquatic-plants/month.200107/msg00165.html and http://fins.actwin.com/aquatic-plants/month.200401/msg00286.html and http://fins.actwin.com/aquatic-plants/month.200205/msg00527.html and specifically http://fins.actwin.com/aquatic-plants/month.200107/msg00463.html where you mention 1.0 ppm Fe.

A fellow Swedish aquarist have a GH of median 14 and max 20, and recently discovered he had to bump up the trace/Fe-amount to about 1 ppm to get better plant health.

So here I go again with my why-questions to gain more knowledge of plant physiology without having any problems.

Why do plants need more traces with hard water? Antagonizing effects?

 

Re: Why harder water = more traces?

I've recently begun to dose 5 tsp CaCl2 + 3 tsp MgSO4 (300 litres tank) after water change to be on the safe side with GH. My Ludwigia glandulosa have now very nice leaves - but the whole tank have been lacking pearling and colors and I have had some algea troubles (Cyano (with 40 ppm nitrate-dosages from KNO3), BBA, thread algae, Cladophora, dust algae) despite big wc:s every fourth day and really high macro levels. The really nasty part was that the pearling was nil after each wc, something that to me screams something is very wrong.

So now I have also bumped up my traces and now my Rotala wallichii have turned a whole new pinkish intense color and the pearling is great.

 

Re: Why harder water = more traces?

Will do. The only nutrient I've always been very reluctant to dose much of is micros, despite your and Claus Christensens advice. I always seem to get a lot of thread-algae when I dose much iron (especially Seachem Iron) or micros, but the same time I've managed to micro-limit the tank from time to time - but before my GH-raising it showed up as very white new growth so it was easily corrected.

Now I will keep the micro-levels higher as you say.

As when I raise the iron levels fast with radically higher dosages and get more thread-algae I've also noticed dust-algae coming as soon as I raise PO4-dosages fast - but the dust-algae only hangs on for a week or two if I keep the high dosages and keeps it steady high.

Will be fun to keep the high micros and see if it's working the same way.

I have about 22 ppm Ca and 2-3 ppm Mg from tap says my water company, but my Hagen Ca-testkit says about 15 ppm Ca. There should be enough I guess but now with my high CaCl2-dose my L. glandulosa looks good again.

But I will try half the dose.

Yes I do. I usually try a couple of different aquascapes in the tank each year where I redo the substrate. Now I've had hair-grass only for a while so I havn't been able to deep vacuum - I only sweep each section and fluff it so organics get out of there.

And man I pick and prune. A couple of hours each wc. I do it because I manage to keep everything neatlooking despite some trouble with dosing. I check my CO2-bubble-rate and pH each day now that the contest are coming up. Picky with picking really pays of. Every time I'm around the tank I usually remove algae I see.

Yes, this I've really noticed. If I get lazy with the vacuuming of the hairgrass or fluffing the plants things get sour rather fast.

Thanks again for all the advice!