A question about pintos dropping eggs

[Rehab]

Hello,

 

So, I have pintos that I have been keeping for years... They are mixed (black and red), with different patterns, and they used to breed insanely before. I think at one point, their numbers were close to a 1,000, so I had to keep rehoming them.

 

However, for this year, they just keep dropping the eggs and I have no idea what the reason is... 

 

They do get berried and I see them fanning quite often, but they drop their eggs pretty soon after a few days or weeks. 

 

The thing is, I have another tank right beside the pinto tank, which started out with EBBs (but bad strain so now it's a mixture of light BBs ~ EBBs), and they are still consistently breeding. 

 

They have the same plants, same substrate (ADA Amazonia, although pinto's substrate is like a year older), same water, same salty shrimp gH+, almost the same TDS, sitting in the same room, similar temp, same food...

 

I kinda stopped measuring the parameters since last summer, because they have been staying consistently at:

pH ~6.0 (ADA Amazonia)

gH ~5~6

kH <1

TDS 100~120 (when it comes time to top up or change water, it becomes around 120).

temp ~ 22C

ammonia 0

nitrite 0

some nitrate

 

-- I would have to re-measure them again, but both tanks have been staying at these levels for a longgg time.

 

Any tips or suggestions would be much appreciated... Why are they dropping their eggs all the time...? :(