[davidpm]

There is some nasty smelling water in the bilge. Not clearly holding tank water but it may be.
Is their some dye I can put in the tank to find out.
What is it called where do I get it.

Do you think food coloring would work?

 

[merc2dogs]

Food coloring would work, I normally use about 6 packs of unsweetened kool-aid mixed in a gallon of water for a very intense dye.

Ken.

 

[RichH]

You can also slightly pressurize the empty Holding tank (2-3 psi) and check the area under suspicion with a mix of dishwashing detergent/water, then looking for the generation of 'soap bubbles'.

 

[TQA]

You can also slightly pressurize the empty Holding tank (2-3 psi) and check the area under suspicion with a mix of dishwashing detergent/water, then looking for the generation of 'soap bubbles'.

DO NOT PRESSSURISE YOUR HOLDING TANK TO 3 PSI.

Life is likely to get interesting and messy if you do this. Assuming the tank has a side 2' x1' the force created by a tank overpressure of 3 psi is 12 x 24 x3 is 864 lbs; do you really want to see if your tank can withstand this sort of force.

 

[RichH]

DO NOT PRESSSURISE YOUR HOLDING TANK TO 3 PSI.

Life is likely to get interesting and messy if you do this. Assuming the tank has a side 2' x1' the force created by a tank overpressure of 3 psi is 12 x 24 x3 is 864 lbs; do you really want to see if your tank can withstand this sort of force.

That's totally ridiculous !

Just the **weight** of static height of a 2 ft. of water in tank will generate 2 / 2.31 ~ 1 psi. (~432 lbs. at the bottom of a tank of your dimensions)....
For water, 2.31 vertical feet (of depth) generates 1 psi pressure !!!!!

Low pressurization is quite suitable and is often used in industry for checking leaks in most (including plastic) empty tanks. 2-3 psi (bottom) pressure would equate to filled tank that is water filled to ~4-6 ft. deep. (and this does not include any 'g' forces nor impacts normally associated with normal sailing conditions).
Checking via 'vacuum' however may implode the tank.

 

[scottyt]

i would never think of putting pressure in my holding tank, the weight of the water in it is different than air pressure, air pressure will bow the tank out. the tank is sitting on something which takes the weight, the top does not.

i also would not use koolaid packs either, it is very acidic. we used koolaid to clean stainless toilets in the navy, as well as to shine pipes. food coloring would be safe thou, or go to a art supply and buy water color tints. another safe option is guys who work on pools have dyes they use to find leaks, it does not stain the pool.