Can I Adjust Macro Solution? - PPS Analysis and Feedback

Nevermore · 01-02-2009, 07:09 PM

My hygrophila corymbosa compacta has holes on the older leaves so I'm wondering if I can adjust my macro solution slightly and add more K2SO4. Or will this throw everything out of balance?

wet · 01-03-2009, 03:57 PM

Sure, especially since you cannot reliably measure K to maintain PPS-Pro's target; however, if K is your limiting nutrient you should expect N and P to drop. Perhaps of interest is, imo, this is where the target/maintenance method school clearly surpasses EI's school: you guys make little adjustments and your target ratios should mean you have enough P and K, anyway (verify with your calibrated test!). EIers who follow guides or crews over experience tend to dump, which can throw it out of whack if there is not clear excess.

A strict PPS-Pro-er whould probably just say to add another half a mil, though, which covers any increased uptake if the ratio holds up. Remember that this method clearly states minimum targets which only increases as plant uptake increases.

Edward · 01-04-2009, 07:22 AM

There could be more reasons why the plant has holes. I bet it is not in new leaves but rather in the older ones grown under previous conditions before the aquarium microbiological system stabilized. It is common for plants to drop such leaves and start fresh. Another reason may be low light penetration to the deeper areas and other plant shading. If you decide to increase K dosage then make additional solution with only K2SO4. The original PPS-Pro solution is already at 70% of maximum solubility and will not dissolve more salt.