Shower drains can be safely cleaned with enzyme-based cleaning compounds that can gently help eliminate clogs containing grease, hair, calcium build-up, rust, toothpaste and more.

QUESTION: I heard warnings against the use of harsh chemicals to try to clean out drains. So what can I do about the clogged drains in my 51-year-old house? My shower can fill up with two inches of water sometimes before it drains out.

ANSWER: It is safe to use enzyme-type drain cleaners. However, using that type of drain cleaner is generally a slow process for clearing clogged pipes. You might have to pour a little into each drain and wash it down, and then repeat the process again later. Using harsh chemicals is dangerous because they can often eat away at the inside of the pipe. Often the corrosion that causes slow drainage is actually holding pipes together and keeping them from leaking. The best idea might be to have a plumber use a camera inside the pipe to see what’s really happening. If tree roots are blocking the pipe, a plumber might have to use a “snake” to grind them out or a hydro-blast process of some kind to push the blockage out.

Q: Our guest bathroom has almost no cold water available in either the shower or the sink. The hot water faucets work fine, but turning on the cold water faucets only produces a dribble of water. What’s going on?

A: If it was only one faucet that was affected it might be easier to figure it out. But since the entire bathroom is affected, you probably need to call a plumber to do some investigating.

Q: I had bids from two air conditioner/furnace contractors, and I’m very confused about the details. My current HVAC system is 22 years old. I want the system to run quietly because it’s located right next to my bedroom. I don’t understand what a “variable speed” AC is supposed to do.

A: We generally advise homeowners to get at least three estimates from contractors on new air conditioner/heater units. You should notify the contractors in writing that you must have a quiet system to ensure better results. The term “variable speed” simply means that the AC blower only operates at the speed needed to cool or heat your home. In March and April when it’s just starting to get warm, it will run on low speed and be a lot quieter. So if you don’t have variable speed, the AC will be much noisier than you want it to be.

Q: What causes blossom-end rot on tomato plants?

A: When blossom end rot occurs, the bottom of the tomato turns black and rots from the bottom up into the fruit. Typically, this is due to a calcium deficiency, which may seem surprising. You wouldn’t think that would happen if you’re using our naturally hard and calcium-rich water for irrigation, but it does. However, you can control the problem by spraying special liquids containing calcium on plants or by using special kinds of fertilizer. Sometimes this problem occurs, however, due to inconsistent watering. So, water on a consistent schedule.

Q: We have some pigmy palms with frost damage on the tops. We covered them at night, but they still froze. Can we save them?

A: They can be saved, but don’t prune out the brown frost-damaged areas until new growth emerges. Even then, you don’t want to take off the whole frond just because it’s partly damaged. So, you may have to live with partially dried-up fronds for a little while.

For more do-it-yourself tips, go to rosieonthehouse.com. An Arizona homebuilding and remodeling industry expert for 29 years, Rosie Romero is the host of the Saturday morning “Rosie on the House” radio program, heard locally from 8-11 a.m. on KNST-AM (790) in Tucson and from 9-11 a.m. on KGVY-AM (1080) and -FM (100.7) in Green Valley.