New to the hobby - Mixing station problem

[FoolintheRain]

So I would like to start by saying I can't express enough how helpful and knowledgeable everyone on this forum has been to me as a lurker over the past years. I have wanted a reef tank since I was in grade school and am finally in position in life to invest the time and $$$ to dive in. Thank you!

So just to get started, I am planning a build for 220g tank with a sump/refugium that have all been ordered but will not be delivered for another month or so. In the meantime I got 2x 50 gallon Norwesco tanks plumbed up for a mixing station a few weeks ago and mixed my first batch of salt to get some dry rock wet while I wait for the tank. The first batch of salt filled both brutes and I noticed a slight brown tint to the tank compared to the RODI tank. I mixed another batch of salt a few days ago and it has been recirculating continuously but now the entire inside of the tank has developed a brown film. It is setup in the garage so there is some ambient but never direct sunlight. I am also using a new hot water heater recirculating pump for now since I had a brand new one that never got used. Water was heated to 78 degrees, Tropic Marin Pro Salt, 6-stage BRS RO/DI reading 0 tds. Any ideas on what this could be or what I should do to determine what this is?

 

[Billdogg]

Looks pretty normal to me. Depending on the salt you are using it may be leaving an organic film. I clean mine about once a year.

 

[FoolintheRain]

Glad to know this seems normal. If this is happening after a few weeks should I clean the tank more frequently? Will the growth have any effect on the water quality?

 

[AJsReef]

Glad to know this seems normal. If this is happening after a few weeks should I clean the tank more frequently? Will the growth have any effect on the water quality?

It's personal preference, should not impact your tank. I try to clean mine every 6 months but I've heard some never clean mixing tanks. If your RODI water is going in at 0TDS and you're only adding salt to it not much to worry about. Although, you may have less build up if you only circulate and bring to temperature before a WC