Black particles in high flow hot water (HW tank with Hydrojet)

[daryl00]

I'm hoping this helps others determine whether this is their issue (and figuring out this mystery). Key points in the issue:

1. Only appears in hot water
2. Black particles will smudge, but if you let it dry, you can "roll it up" between your fingers (rubbery?)
3. Seems to appear mainly in bath tub faucet. For us, that is the highest flowing faucet (2x at least)
4. Can appear in other faucets, especially faucets in the same bathroom, but seem to require turning on bath tub faucet on full for a while first.
5. Flushing tank has not helped. Particles continue to appear shortly after (within 2 days)

This issue has been baffling us because we don't have any flex piping any where near the hot water tank and the pattern of "which faucet and how much" didn't seem to point to any one answer. However, we've finally decided to get a new tank installed (happening soon) because I've noticed one thing: if I open the bath tub faucet only part way so that the flow is similar to the other faucets, I don't get any particles. I would fill a 5 gallon bucket 6 times and get nothing if the flow is low, but if I open that faucet all the way, I'll start seeing particles by the 3rd bucket. This matches what occurred previously when I always opened faucet all the way. I then noticed that opening this bath tub faucet on full was also a prerequisite to seeing particles in other faucets.

This is also the first hot water tank we've had with the "Hydrojet System". The system is described as having water ports near the bottom of the tank so that when cold water flows in, it stirs up the bottom of tank in order to prevent sediment build up. That seems to match the pattern of occurrence with the black particles (that is, we need to turn on a high flow faucet which would stir up the bottom of tank sufficiently).

This system sounds like a good idea, but for a 3 year old tank to be almost constantly spitting out these black particles (we've noticed it daily for the past few months), something doesn't seem right. Surely there can't be this much buildup on a daily basis. Not to mention the fact that the particles seem rubbery. If it really is just normal buildup (magnesium oxide, or whatever), it would at least put my mind at ease that we haven't been consuming broken down rubber/plastic for months.

 

[Reach4]

Good chance it is a sulfur compound. Do you smell H2S ("sulfur") smell from your hot water?

https://globalimageserver.com/FetchDocument.aspx?ID=442e1e42-1e4a-4ada-81db-9b030030f470

 

[Sponsor]

 

[daryl00]

Good chance it is a sulfur compound. Do you smell H2S ("sulfur") smell from your hot water?

If there is any smell, it's very faint. Pretty sure it isn't sulphur smell.

 

[daryl00]

Service guy came by and replaced the anode rod (from magnesium to aluminum) and flushed the tank again. It's been almost 2 weeks since and it's been a lot better. I think anything that does come out is left over from before.