Title: Coolant recommendation for Antminer S19 Hydro – circulation pump issues

[calverajardaeliska]

Hi everyone,

I'm looking for recommendations for a suitable coolant for my Antminer S19 Hydro.

I'm currently using Aquacomputer DP Ultra, but I suspect it might be causing issues with my circulation pump (similar to a Grundfos pump).

After the system has been shut down for a longer period, the pump rotor becomes difficult to turn manually. However, after rotating it several times, the resistance gradually disappears, and the pump starts and runs normally.

I suspect the coolant might be contributing to this issue.

My cooling loop:

1× Antminer S19 Hydro

Materials: copper, brass, and aluminum

No antifreeze protection needed

Maximum coolant temperature: approximately 60°C

I'm looking for a coolant that:

Is compatible with copper, brass, and aluminum

Contains corrosion inhibitors to protect against galvanic corrosion

Prevents bacterial and algae growth

Is suitable for continuous operation

Is preferably available in the EU

Has anyone experienced similar pump issues with DP Ultra? What coolant would you recommend for this setup?

Thanks in advance for any advice!

[zina13]

That stiff-rotor-after-idle symptom is usually DP Ultra residue settling on the rotor when the loop sits still.

I've seen the same thing with guts that sit warm and static for hours. If you don't need antifreeze, a low-biocide glycol-free coolant made for mixed copper/alu loops is the safer bet at 60C.

[BitMaxz]

Bitmain never mentioned a recommended coolant for hydro units.

Other said you need to use "Antifreeze/Pure water/Deionized water" coolant those are working ones for hydro units.

You can find the source here: https://bitcointalk.org/index.php?topic=5544714.msg65593576#msg65593576

For Zeusbtc recommendation, they have ZY-601 antifreeze coolant and Syscooling water cooling coolant that works on hydro units.

[MergedHash]

A pump rotor that is stiff after a long shutdown and frees up after a few turns usually points to deposits or a film drying in the tight gap between rotor and can, not to the pump itself. Pre-mixed PC coolants like DP Ultra contain dyes, surfactants and corrosion inhibitors that can leave exactly that kind of residue when the loop sits still, especially if some water evaporated.

What has worked for hydro units:
- Flush the loop with distilled or deionized water, run it for a while, drain, and repeat until it comes out clear.
- Refill with deionized water plus a proper inhibitor/biocide, or with about 25-30% propylene glycol in DI water if there's any freeze risk. Avoid dyed or "UV" coolants and anything with particles.
- Keep conductivity low (DI water), use a mesh filter before the pump, and check for any biological growth.
- During long shutdowns, either run the pump for a few minutes every few days or drain the loop. Standing coolant in the pump gap is what causes the sticking.
- If the rotor is still stiff after a clean flush, pull the pump head and clean the can and impeller. Bearing wear also shows up this way.

As mentioned above, Bitmain doesn't publish a specific product for the S19 Hydro; antifreeze or DI water is what's used in practice.

[BitMaxz]

A pump rotor that is stiff after a long shutdown and frees up after a few turns usually points to deposits or a film drying in the tight gap between rotor and can, not to the pump itself. Pre-mixed PC coolants like DP Ultra contain dyes, surfactants and corrosion inhibitors that can leave exactly that kind of residue when the loop sits still, especially if some water evaporated.

What has worked for hydro units:
- Flush the loop with distilled or deionized water, run it for a while, drain, and repeat until it comes out clear.
- Refill with deionized water plus a proper inhibitor/biocide, or with about 25-30% propylene glycol in DI water if there's any freeze risk. Avoid dyed or "UV" coolants and anything with particles.
- Keep conductivity low (DI water), use a mesh filter before the pump, and check for any biological growth.
- During long shutdowns, either run the pump for a few minutes every few days or drain the loop. Standing coolant in the pump gap is what causes the sticking.
- If the rotor is still stiff after a clean flush, pull the pump head and clean the can and impeller. Bearing wear also shows up this way.

As mentioned above, Bitmain doesn't publish a specific product for the S19 Hydro; antifreeze or DI water is what's used in practice.

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