API Root Tabs turned my sand reddish

I got API root tabs in hopes they'd do well enough to help my Amazon swords grow, as they were yellowing. I put 2 tabs into one side of my divided 10 gallons last night, and now see reddish orange spots all over my black sand. My setup makes the tank have 3 parts (1 4ish gallon side with a betta, a smaller MAYBE one gallon space, and another 4ish gallon side with a betta), the tabs being put into one of the betta slots. The sand in that slot and some of the sand in the middle section has turned rust colored. I've heard some people say similar things about these tabs, but does anyone know why this happens and what it is?
Also worth mentioning that the plants seem to have gotten worse, now browning.

 

It's probably just the fertilizer itself coming up through the sand. Hopefully the plants will turn around, assuming the lack of ferts was the issue to begin with. I've heard a lot of complaints with this tabs in particular but they were usually complaining that the tabs spiked their parameters (ammonia etc).

 

I just logged on looking for answer to the same question. I added 4 tabs two days ago and now I have reddish brown patches on my black sand.
I wondered if it's the tabs (the only new thing) but they don't seem to bee where I put the tabs.
Will it go away/dissolve?

 

It's most likely to be the root tabs. Sometimes compacted sand will turn black/brown as waste accumulates under it and gets compacted, but that process usually takes months. As to whether it'll dissolve, it's hard to say, but your best bet is to try to vacuum it out if possible.

 

The spots literally appeared overnight. Would this cause the water to cloud a little too?
Hard to photo, but here:

 

I've read that these tabs can cause nutrient spikes which would in turn cause cloudy water or a green water bloom.