Vodyani cannot have other population types by design (like Umbral Choir) so their bonuses for Ecologists (lvl 3 and 4 depend on a number of different populations per system) are pretty meager and flat - +2/+4% science and industry (4% while a Republic). 

A great bonus is Eco 0 law, but it comes at a price of fighting tooth and nail to keep it, as Vodyani pretty much hate being anything other than Religious.
They use default Eco-laws like anybody else(barring Gene Hunter i.e. Horatio affinity). Here are other laws and their bonuses, () siginifies Republic law intensification effect

Hardship Ready		Power - 0	+15 on Systems (Hissho :keii bonus?) * Enables colonization of Telluric (non-gas) planets. However, you will suffer a -50 %(-25%) FIDS penalty without the correct colonization technology
Green Fertility Bill		1	+2 (+3) per pop on Anomaly +5% (+10%) FIDSI per Anomalies on Colonized Planet on Systems
Cool Copies Clause		2	+2 (+4) per pop on Planets -25% (-40%) Luxury cost for increasing population growth rate
Power to the People Act		3	(Horatio only) +2%(+4%) per Spliced Population on Systems (Other Factions) +2% (+4%) per Population Types on Systems
All Hands Dictum		4	(Horatio only) +2%(+4%) per Spliced Population on System (Other Factions) +2% (+4%) per Population Types on Systems

Umbral Choir have their own unique ecologist(and other) laws depending instead on Backdoors and their superpops - Shadows.

LVL 0 Default

LVL 1 Default

LVL 2 Umbral Anglers "Private Vacuum Drift Fishing Bill" (replaces "Cool Copies Clause") +2 (+4)per Umbral Shadows on Home System. +2 (+4) per Pop on Planets

LVL 3 Backdoor Boon "Siphoning Enemy Resources Act" (replaces "Power to the People Act") +1% (+2%) and +1% (+2%) per Backdoor, on Home System

LVL 4 Elite Shadows "Elite Shadows Identification and Training Mandate" (replaces "All Hands Dictum") +20 (+30) per Turn per Umbral Shadow pop. +10 FIDSI (+15) per Umbral Shadows pop on Home System

Keep in mind that Umbral Choir can have multiple backdoors and a whole system composed of Shadows, thus giving us double digits %, while Vodyani can achieve at most 4%, but will most likely keep it at 2%. 

Eco Umbral Choir with just 2 backdoors(basically nothing) is equal to Eco Vodyani sacrificing 2 most powerful laws.

Are they balanced enough or should devs enhance Eco Vodyani further by cranking the numbers up or base it on something other than population e.g.  on "Brainwashed Minor Civs" ?

I genuinely don't know, as I usually don't play Vodyani, but ask I must, if this meager 2% is balanced for a price of giving away other Parties and their meaningful laws.

*Also: I have +15 Happiness and -25% FIDS effect when it's Horatio Dictatorship...yet it drops it's +15 bonus after shifting to Republic or Democracy(then it's also -50%). I'm perplexed. 

Edit: I've been told in another thread that these dictatorship-power law convergences are designed for balance purposes but are as of now - hidden- because reasons. Sight. 

koxsos wrote:

*sigh

I second the notion that vodo eco high tier laws suck and could use a second look.
Bring up a proposition.

I've proposed, but gingerly: "Are they balanced enough or should devs enhance Eco Vodyani further by cranking the numbers up or base it on something other than population e.g.  on "Brainwashed Minor Civs" ?

I genuinely don't know, as I usually don't play Vodyani, but ask I must, if this meager 2% is balanced for a price of giving away other Parties and their meaningful laws."

Vodyani with 2 Brainwashed Minor Civs (realistically) would produce up to e.g +12% Science and/or +12% Industry on Republic. 

In their default Federation that would be 6%.  It's still better than eternally flat 2 or 4%, no matter how many Civs would be subjugated.

Power to the People Act (Vodyani)		3	(Vodyani only) +2%(+4%) on Systems +2% (+4%) per Brainwashed Minor Civilization on Empire
All Hands Dictum (Vodyani)		4	(Vodyani only) +2%(+4%) on Systems +2% (+4%) per Brainwashed Minor Civilization on Empire

This as a consequence would force on Vodyani to moderate their rush, as they would relegate some resources to defend their subjugated, albeit profitable Civs, that would be harassed by conscious players. More Minor Civs would mean more spreading thin with its pros and cons, to keep it in check.

mm, perhaps +% per pop on system, would do nicely. I mean what's the max vodo system capacity? 3/5/7/9?

koxsos wrote:

you can invade them to take them away I believe. All others have the bonuses on per system basis, I would say getting ecos forced law with vodyani is snowball enough on it's own.

Duly noted and edited, though a flat bonus X per systems is virtually a flat bonus X per empire. Empire bonus % from Brainwashed Civ needs to stay though, due to constraints. "Per pop" or "per system level" would output much higher values, quickly achieving 20% and above.