Customer concerns about algae / growth in combi storage tank

ABSolar

Hi all,

Just had a customer express concerns for bio growth in the epdm lined 400 gal combi tank I installed for him.  Only thing I've added was baking soda for ph control.  Mucho copper coils in the tank, by the way. And the water is stagnant, seperate heat loops either add or subtract heat from the tank water.

 

I just read that most roofing epdm liners have an algecide and fire retardant built in.  I am presuming that the STSS tank came supplied with a roofing epdm liner, not a Firestone pond-fish safe liner. 

The fact that the atmospheric tank has a lid to restrict additional nutritional matter/ dust for algae & other bio stuff to grow on, coupled with lots of copper ions in the tank water AND temperatures of the water reaching 180 at the bottom occasionally in the summer makes me think I have nothing to worry about.  Yet it does give me pause to think...

 

I have suggested the possible use of a gentle fish safe algecide used for Koi ponds w/ epdm liners.  Any thoughts?

AB Solar

Mark Eatherton

Copper sulfate crystals...

Copper sulfate is commonly applied to ponds to control algae blooms.



Available from your local hardware store (RootX or Root Destroyer) bluish green crystals.



I use it in my boilers condensate trap and neutralizer buckets. I have two different "experiments" going on right now as it pertains to bio growth in condensate buckets.



In Denver, I keep my condensate neutralizer/receiver/pump bucket loaded with sulfate crystals. I use to have to cable my sewer out for roots once every 2 years. Have gone for 6 years now without a hitch.



In Heeney, I have a 2 bucket system. One for receiving/neutralizing and one for FAST pumping/discharge to my leaching field. The first bucket has lots of copper fittings in it (experiment to see how fast/bad copper degrades on the pH of condensate). The first bucket has NO algae in it. The second bucket has some slight discoloration indicating that something is going on.



HTH



ME

thoughtfulTom

180 is too hot

AB Solar - those STSS tanks don't like high temps. We limit our bottom sensor to 175F (very little stratification in a drainback tank while it is loading).



In your case, if you are using glycol (ie loading through copper coils) 180F at the bottom could mean significantly higher temps at the top. A top sensor is critical for your installation, as well as a way to ensure the (hottest) water doesn't exceed 175F (the EPDM that Sven uses degrades notably above 180F - not sure why he didn't use a higher temp rated EPDM).



Now, after about 5 years of using STSS tanks - I haven't see any algae growth at all in the tanks that see 170F - is your customer worried about the possibility, or is there algae growth there now?

Kevin_in_Denver_2

Complete darkness = no algae?

Come to think of it I have seen some sort of algae or plant growing in high temperature hot springs. Temps above 150F even. Never seen it in any solar tank, though.



My working theory is that since algae is a plant, it needs at least a little bit of light to grow.



(But don't mention that fungus likes the dark.)

Tom in Maine

Algae

If the tank temps go above 140F, most "stuff" that grows in these tanks will never develop.

The only time we have ever had a bad problem with stuff growing in tanks was with a solar tank that we used as a heat source for a heat pump. The tank was usually chilled down to 60F. When I opened it, I had what appears to be 600g of egg drop soup.

It was full of slime mold.

I cleaned it out, and did not get sick(!) The tank was otherwise fine.

Every other tank that we have been into has shown no signs of nasty stuff growing.

We have been doing this about 30 years. Although we used PVC liners up to very recently, we do get into EPDM lined tanks and if the EPDM is intact (we usually see them when the customer needs a new liner that is not EPDM) there is still nothing organic growing.



I would just follow the STSS pH recommendations to help prolong the liner life and keep it at 165-170F max.



Adding anything other than what the manufacturer recommends might void your warranty.



tom in maine