seeds_3 is the order-3 SEEDS exponential SDE solver. Because it integrates the diffusion trajectory very accurately, it preserves composition and text remarkably well even at high denoise — great for refiners.

The problem: ComfyUI ships a configurable node for seeds_2 (SamplerSEEDS2) but none for seeds_3. Selected from the KSampler dropdown, seeds_3 always runs at eta=1, s_noise=1 — full-strength stochastic noise injection, which shows up as grain. There was no way to turn it down.

This node wraps the public comfy.samplers.ksampler("seeds_3", ...) API and exposes eta, s_noise, r_1, r_2.

The key behavior

In comfy/k_diffusion/sampling.py, sample_seeds_3 gates all noise injection on:

inject_noise = eta > 0 and s_noise > 0

So at eta = 0, every stochastic term collapses and seeds_3 becomes a clean, fully deterministic 3rd-order exponential ODE solver:

keeps seeds_3's high-denoise structure / text preservation,
adds zero grain.

Recommended use (high-detail refiner)

A tiled Flux refine that adds detail without grain or composition drift:

SEEDS-3 Sampler with eta = 0.0 (clean). → SAMPLER
(optional) feed that SAMPLER through a detail-injection sampler (e.g. Detail Daemon) to add micro-detail deterministically instead of via grain.
→ UltimateSDUpscaleCustomSample (or any node with a SAMPLER input).
Scheduler: ays (e.g. via ComfyUI-PPMSchedulers).

Because structure preservation comes from the solver, you can keep denoise high (0.35+) for detail without the usual composition/text drift.

Param	Default	Notes
`eta`	0.0	0 = deterministic / no grain. Raise for stochastic texture.
`s_noise`	1.0	Only matters when `eta > 0`.
`r_1`	0.333	First intermediate stage (1/3).
`r_2`	0.667	Second intermediate stage (2/3).

Install

cd ComfyUI/custom_nodes
git clone https://github.com/lookuters22/ComfyUI-SEEDS3Sampler

Restart ComfyUI. The node appears under sampling/custom_sampling/samplers.

License

MIT. This node contains no ComfyUI source — it only calls the public sampler API.