A beginner's beginning - maybe!

[Mau]

Hello folks,
early next year I plan to dismantle my low-end brackish and try marine.

What I have:
- a 240 lt tank
- room for a 43 x 35 x 40+ cm sump in the cabinet (LxDxH). <60 liters
- a quite hard tap water, with stable 40 mg/l of NO3

What I'm imagining:
- FOWLR (about 20+ kg)
- as many macroalgae as I can find here (Europe :sad2 in the DT
- the best HOB or in-sump skimmer I can afford
- a lump of chaetomorpha (and nothing else) in sump

The main question is:
- would a system as above be able to handle the total nitrates (tap water + bioload)? I know, the question is badly posed (lots of variables unspecified), but generally speaking: there must be out there an indication of the needed biomass of macroalgae able to export a given amount of NO3?
- RO is not an option (I find it unethical to run a machine with a 75% rate of waste water)
- I may be able to collect rainwater, though..... Sure, after I check it, but air quality is quite good here...

THANKS!

 

[gone fishin]

The system as described I do not know if it would do what you want. I believe you would have to try it and see what your results are long term. I would assume European tap water is similar to the water here in the states. It could have things much worse for a tank than nitrates.

As far as your ethical concerns for RO/DI, have you considered repurposing the RO/DI waste for such things as the washing machine, toilet, watering plants. Good luck

 

[Mau]

Thanks Tony,
I never checked phosphates, but apart from nitrates there's nothing else bad here in tap water. They don't even add chlorine, I've been damping it straight in the tank for 4 years now.

Your suggestion about repurposing sounds a lot like storing around A LOT of water. I'll give it a thought, joting down some numbers, but I'm skeptical on long-term feasibility...

 

[homer1475]

With a tank that size, you would want to store a lot of water just for emergencies. its not like your fresh tank where you can just dump water in if needed, you need to mix salt, bring up to temp, then dump it in the tank.

I would still look into RO/DI, there is a lot of microalgae in your water if their not adding chlorine to kill it, or flush out the pipes.

 

[nmotz]

I think the answer you'll continue to get from most people is that it's tough to know how successful you'll be because we don't know exactly what is in your tap water.

However, my initial thought is that if you have enough macroalgae to absorb nutrients and you only want to keep fish then this might work. Ultimately it may be something you have to try to find out for certain. Trial and error is how most of us learn in the end.

 

[Mau]

Thanks folks.

Nmotz, it makes a lot of sense. I got much the same answer from the local shop here, "as long as you keep fish only, they'll be all right". I can surely start with RO water, and then slowly make water changes from tap, following closely.

Anything against rainwater?