tap water for seagrass tank?

[Mark]

I'm in the process of setting up a new seagrass tank. I kept some thallasia rizhomes in a 6 gallon eclipse many years ago, but it was filled with mud collected in a mangrove lagoon near Jupiter Florida. I think the reason it worked for a short while was because it was in front of a sunny window. One of the other things that may have helped is that I topped off with tap-water. My tapwater here in the burbs north of Atlanta registers a TDS reading of 30 PPM. I haven't ever really tested the phosphate or nitrogen levels. I plan to though.

The new tank will be a 40 gallon breeder, lit with a 175-watt metal halide horizontal pendant. This tank was filled sea water made from my RO/DI unit, and I top off with RO/DI. This processed water has a TDS reading of 0 PPM.

As I continue to read about people having to supplement nitrogen and phosphate to their marine planted tanks, I'm wondering if there is really much harm in using tap water to top off? With my reef tank, I use RO/DI to help avoid the very things that plants and algae benefit from. The only downside to using tapwater in the planted tank is the introduction of silicates, which could spur diatom blooms.

So the question is, do you guys use RO or just some carbon filtered tapwater?

 

[Samala]

Having some extra silicates, or extra iron, alone.. dont seem to spur diatom blooms. The plants/macro typicaly do a good job of keeping it out of their reach if they're growing well. My snails must graze down the beginnings of blooms in my tanks if its happening. It really takes a lot to prompt a diatom bloom once established.. like falling alkalinity levels. But again, thats a limitation on the plants for growth, in that example, carbon.

That said, I use carbon filtered tap water. My tap water is really not the greatest, so sometimes I'll dilute 50/50 with RO water if I'm feeling especially paranoid. A nice attribute of my "lovely" tap is that, using that, I have never had to dose phosphates so far. Just nitrates so growth can keep up with the phosphate load. Honestly, its the nitrates that really make a mess of algae blooms. Having phosphates alone doesnt guarantee a problem from what I've seen.

The few things about tap that I wonder about are... fluoride? Does this make my jawfish have nice shiny white teeth?

>Sarah

 

[Mark]

The few things about tap that I wonder about are... fluoride? Does this make my jawfish have nice shiny white teeth?

lol.

based on your input, I will probably start with 50/50 ro/tap, until the plants and algae get established. Then I will start topping off with tap. Wow! This tank is going to be so much less hassle than my reef.

 

[piercho]

Mark,
I've kept seagrass for a couple of years and use tapwater for evap makeup via limewater. Our tapwater here where I live is pretty good, though, just rainwater straight off the North Pacific. I also get the benefit of some ions precipitating out when making it into limewater.

I don't tinker with nutrient additions, just feed the fish. I have made daily small additions of chelated Fe, though. From what I've seen of Sarah's tank (above), who does tinker with nutrient input, she gets faster and denser growth of seagrass than I do at lower levels of irradiance.

 

[Mark]

Thanks Howard. I live north of the city, so you could say I'm sort of upstream from it. But our water here goes through phases. Sometimes, nutrients can shoot up due to fertilizer run off and such from heavy rain. But my tds meter keeps an eye on that for me.

I spent a couple of years living north of you in Alberta... Now that was some clean tasting water! I imagine it's very much the same in your state.

 

[piercho]

The wife's from Edmonton AB. Yeah, the surface water here West of Puget Sound is as good as it gets, we are fortunate. Mostly I worry about whats leaching out of the pipes (Cu, Pb) here at the terminal end.

 

[Mark]

Edmonton, small world. I went to Strathcona highschool, spent lots of time drinking coffee on whyte.

 

[graveyardworm]

The only thing I would suggest if you havent done so allready is to have your tap tested especially metals like piercho said copper and what ever that other one is.