Can any aquarium owners help with gunge in rainwater harvesting attic storage tank?

slipstream

I have an unusual query which I hope you guys might be able to help with.

I have a rainwater harvesting system which involves an underground rainwater tank and pump connected via a pressure switch/pump controller to a storage tank in the attic which in turn feeds toilet cisterns.

What has this to do with aquariums!?

Well, some of our toilet cistern fill valves are not closing due to black gunge in the water. When this happens they cisterns continually overflow into the bowl.

Looking at the attic tank, there is quite a lot of floating material and it is in a a warm location which I would guess would promote bacteria growth.

This is a where I thought you guys might be able to help.

What would the cheapest and simplest way to stop gunge getting into the water tank outlet?

Thanks for your help!

Slip

Sleepy

It sounds like algae buildup - is there a lot of light getting into the system somewhere? If you can eliminate the light source, you'd starve the algae. There are chemical treatments available for this in the aquatics market but I'm guessing they'd be prohibitively expensive to use in such volumes as you'd need for this purpose.

An alternative might be to run a protein skimmer (something we use in marine fishkeeping which originated in the world of waste-water treatment). However, protein skimmers need frequent emptying: daily in the case of my small nano reef tank) and I'd question the economies of powering both a water pump and a skimmer versus the cost of the additional water unless you were powering them from a local solar/wind setup.

My experience is entirely based on aquariums though, someone running a pond system might be better suited to advise on this.

slipstream

Thanks Sleepy but I don't think there is much light entering the system anywhere as the underground tank is sealed and the attic tank is in the dark.

There is a coarse steel mesh on the pump and a leaf filter on the underground tank inlet to keep debris out. However, there are leaves etc. in the tank at present as our builders left the cover off some of the time.

Perhaps if I chemically kill the current organic stuff then some sort of unpowered filter which we maintain would be sufficient (or maybe not)?

él statutorio

It sounds like some sort of cyanobacteria to me.

Cyanobacteria flares up if you've got high nitrates and phosphorus. At least in a freshwater tank anyway.

Maybe there's moss or something on the roof and it's coming in from there.

If it was me, and if the water is just for toilets etc I'd try a small amount of hydrogen peroxide in the system to see if it clears it up.

If it's for showers I'd be cautious, especially if you've ladies in the house. You don't want to be giving them blonde streaks!


*edit* it's probably from the leaves, fully clean the system, add a dose of chemicals and you should be set.

slipstream

él statutorio wrote: »

If it was me, and if the water is just for toilets etc I'd try a small amount of hydrogen peroxide in the system to see if it clears it up.

toilets and washing machine (but this also has a mains feed). if hydrogen peroxide would be the best chemical to add, where would i pick this up?

él statutorio wrote: »

*edit* it's probably from the leaves, fully clean the system, add a dose of chemicals and you should be set.

looking in the attic tank, i don't think there is a massive amount of gunge so i think you are right and the problem is a handful of decomposing leaves.

is there some kind of cheap filter/strainer i could use on one of the attic tank inlets/outlets to catch this stuff?

thanks,

slip

él statutorio

slipstream wrote: »

toilets and washing machine (but this also has a mains feed). if hydrogen peroxide would be the best chemical to add, where would i pick this up?



looking in the attic tank, i don't think there is a massive amount of gunge so i think you are right and the problem is a handful of decomposing leaves.

is there some kind of cheap filter/strainer i could use on one of the attic tank inlets/outlets to catch this stuff?

thanks,

slip

Your chemist will sell you hydrogen peroxide.

You could try an old pair of tights over the inlet, cheap and they'll catch everything, but they'll break your heart in the autumn as they'll block a lot.

slipstream

él statutorio wrote: »

You could try an old pair of tights over the inlet, cheap and they'll catch everything, but they'll break your heart in the autumn as they'll block a lot.

i imagine i'll get a raised eyebrow or two when i ask the missus for some old tights!

is there alternative (other than fishnets!) if they do block up all the time?

slipstream

él statutorio wrote: »

You could try an old pair of tights over the inlet, cheap and they'll catch everything, but they'll break your heart in the autumn as they'll block a lot.

one additional option i wondered about was whether a sponge of some sort be better/worse than tights?

él statutorio

slipstream wrote: »

one additional option i wondered about was whether a sponge of some sort be better/worse than tights?

I don't think the sponge would be needed, you just want to catch the leaves etc before they get into the system. A sponge might block too easily.

slipstream

tights installed ... thanks for all the advice!

we'll see how long before they gunge up.

CJhaughey

Sounds like you should install a first flush diverter.

slipstream

CJhaughey wrote: »

Sounds like you should install a first flush diverter.

I've read about these online but I havent seen them suggested by Irish or Ireland UK suppliers. Also at this point it would be difficult for me to retrofit.

I would say a washable 100 - 200 micron filter would probably be the best solution and the tights seem to be helping.

I probably need to throw in some chemicals to keep off anything organic left over from old leaves though.

recedite

I don't see how the chemicals will help, except in the short term. If there is no light getting in, it must be general detritus.
First off I'd go up to the attic tank with a plastic tube or hose and syphon off the debris from the bottom of the tank. You could consider putting in a another pipe into the bottom of the tank, leading to a special tap outside or a sink inside so you can draw off some of this stuff as it collects, without climbing into the attic. And make sure the tank has a lid. The tank connector leading to the toilet cistern would be at a higher level than the the draw-off connector.

Then I'd look at the outdoor storage tank. Going on the same principles, maybe the pump to the house can be raised up a bit so its not sucking up the detritus. Maybe some way of clearing sediment off the bottom can be arranged.
No leaves should be getting in. If the water from the roof landed onto a bucket of pebbles, with a hole in the bottom of the bucket leading into the underground tank, no leaves would get in. The leaves would gather on top of the pebbles and blow away afterwards.